Volodymyr Tsemakh, former commander of Russian-backed separatist forces in eastern Ukraine, sits in a court room in Kiev, Ukraine, Thursday Sept. 5, 2019. A Ukrainian court has unexpectedly released a witness in the case of the 2014 downing of Malaysia Airlines Flight 17 over separatist-held eastern Ukraine. The appeals court in the capital Kyiv ruled on Thursday to release Volodymyr Tsemakh from custody pending investigation. (AP Photo/ Volodymyr Hontar)

Volunteers with the right-wing paramilitary Azov National Corps light flares during a rally at the appeals court, as they protest against release Volodymyr Tsemakh, former commander of Russian-backed separatist forces in eastern Ukraine, in Kiev, Ukraine, Thursday Sept. 5, 2019. A Ukrainian court has unexpectedly released a witness in the case of the 2014 downing of Malaysia Airlines Flight 17 over separatist-held eastern Ukraine. The appeals court in the capital Kyiv ruled on Thursday to release Volodymyr Tsemakh from custody pending investigation (AP Photo/Efrem Lukatsky)

Volunteers with the right-wing paramilitary Azov National Corps light flares during a rally at the appeals court as they protest the release of Volodymyr Tsemakh, former commander of Russian-backed separatist forces in eastern Ukraine, in Kiev, Ukraine, Thursday Sept. 5, 2019. A Ukrainian court has unexpectedly released a witness in the case of the 2014 downing of Malaysia Airlines Flight 17 over separatist-held eastern Ukraine. The appeals court in the capital Kyiv ruled on Thursday to release Volodymyr Tsemakh from custody pending investigation. Writing on the banner: "The appeals court accomplice of terrorism". (AP Photo/Efrem Lukatsky)

Volunteers with the right-wing paramilitary Azov National Corps attend a rally at the appeals court as they protest against the release of Volodymyr Tsemakh, former commander of Russian-backed separatist forces in eastern Ukraine in Kyiv, Ukraine, Thursday Sept. 5, 2019. A Ukrainian court has unexpectedly released a witness in the case of the 2014 downing of Malaysia Airlines Flight 17 over separatist-held eastern Ukraine. The appeals court in the capital Kyiv ruled on Thursday to release Volodymyr Tsemakh from custody pending investigation (AP Photo/Efrem Lukatsky)

Volunteers with the right-wing paramilitary Azov National Corps light flares during a rally at the appeals court, as they protest the release of Volodymyr Tsemakh, former commander of Russian-backed separatist forces in eastern Ukraine in Kiev, Ukraine, Thursday Sept. 5, 2019. A Ukrainian court has unexpectedly released a witness in the case of the 2014 downing of Malaysia Airlines Flight 17 over separatist-held eastern Ukraine. The appeals court in the capital Kyiv ruled on Thursday to release Volodymyr Tsemakh from custody pending investigation (AP Photo/Efrem Lukatsky)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, is about to leave a dock of Kiev court of appeal after the court verdict in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, is about to leave a dock of Kiev court of appeal after the court verdict in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, listens to the verdict of the court of appeal, during his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, listens to the verdict of the court of appeal, during his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, listens to the verdict of the court of appeal, during his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh (L), an Ukrainian man suspected of involvement in the downing of flight MH17, smiles as he speaks with his lawyer after the verdict of the court of appeal, at the end of his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, listens to the verdict of the court of appeal, during his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, listens to the verdict of the court of appeal, during his hearing in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Vladimir Tsemakh, an Ukrainian man suspected of involvement in the downing of flight MH17, is about to leave a dock of Kiev court of appeal after the court verdict in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019 released from pre-trial detention Tsemakh, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Sergei SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, burn flares as they hold a banner reading, "Appeal court is accomplice of terrorists" during a protest outside the court buikding after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, burn flares during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, burn flares during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, burn flares during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, salute during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, salute during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

Activists of National Corps, far right Ukrainian party, burn flares during a protest outside the court building after the court freed the man suspected of involvement in the downing of flight MH17 in Kiev on September 5, 2019. - A court in Ukraine on September 5, 2019, released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he might be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. (Photo by SERGEI SUPINSKY / AFP)

(FILES) In this file photo taken on October 13, 2015 the wrecked cockipt of the Malaysia Airlines flight MH17 is presented to the press during a presentation of the final report on the cause of the its crash at the Gilze Rijen airbase. - A court in Ukraine on September 5, 2019 released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by EMMANUEL DUNAND / AFP)

(FILES) In this file photo taken on November 11, 2014 journalists walk behind parts of the Malaysia Airlines plane Flight MH17 as Dutch investigators (unseen) arrive near at the crash site near the Grabove village in eastern Ukraine, hoping to collect debris from the Malaysia Airlines plane which crashed in July, killing 298 people, in remote rebel-held territory east of Donetsk. - A court in Ukraine on September 5, 2019 released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Menahem KAHANA / AFP)

(FILES) In this file photo taken on November 10, 2014 a pro-Russian gunman stands guard next to parts of the Malaysia Airlines Flight MH17 at the crash site near the village of Hrabove (Grabovo), some 80 kms east of Donetsk. - A court in Ukraine on September 5, 2019 released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Dimitar DILKOFF / AFP)

(FILES) A file photo taken on November 7, 2014 shows parts of the Malaysia Airlines Flight MH17 at the crash site in the village of Hrabove (Grabovo), some 80km east of Donetsk. - A court in Ukraine on September 5, 2019 released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Dimitar DILKOFF / AFP)

(FILES) A file image grab taken from an AFP TV video shows the two black boxes recovered from the crash site of the MH17 jet being handed over to Malaysian officials during a press conference in Donetsk. - A court in Ukraine on September 5, 2019 released from pre-trial detention a man suspected of involvement in the downing of flight MH17, amid speculation he may be used in a prisoner swap with Russia. Ukraine captured Vladimir Tsemakh, accused of fighting for pro-Russian separatists, in June, but he is believed to be a person of interest in the downing of MH17. European lawmakers described him as a "key suspect" and asked Kiev to make him available for testimony in the probe. (Photo by Damien SIMONART / AFPTV / AFP)