An Iranian man convicted in the 1992 murders of four Kurdish dissidents in Berlin has been released from a German prison and is now back home in Tehran.

The undated file photo shows Iranian Kazem Darabi, the main defendant in the so-called Mykonos trial

German officials freed Kazem Darabi and his Lebanese accomplice, Abbas Rhayel, on Monday after 15 years in prison. The two men were given life sentences for murdering the secretary-general of the Kurdistan Democratic Party of Iran, Sadegh Sharafkandi, and three of his associates at a Berlin restaurant.

Darabi told Iranian news agencies in Tehran Tuesday the decision to free him showed his innocence. He said he would write a book giving his side of the story.

The two men were freed under a law that allows early release for foreigners who have served at least 15 years of their sentence. Rhayel was deported back to Lebanon.

The KDPI's U.S. representative, Sharif Behruz, tells VOA that he hopes the release of the two men was not the result of a deal between the Iranian and German governments. He says that if there was a deal, it will undermine Germany's fight against terrorism.

German prosecutors accuse Iran's supreme leader, Ayatollah Khamenei, and then-President Hashemi Rafsanjani of ordering the killings. The accusation infuriated Tehran and led to a temporary freeze in Iranian-German relations.

Israeli authorities had long objected to Germany releasing the men, hoping they could be used as bargaining chips for information about an Israeli pilot Ron Arad shot down over Lebanon in 1986.

Some information for this report was provided by AFP and Reuters.