Palestinian girl Maria, 3, hugs her brother Osama, 18 months, in front of a portrait of their father Dirar Abu Sisi, during a solidarity demonstration calling for his release from an Israeli jail, in front of UNRWA headquarters in Gaza city. (Adel Hana/AP)

A Palestinian engineer from Gaza, held by Israel after he vanished mysteriously from a train in Ukraine, was charged Monday in an Israeli court with developing rockets for the Islamic militant group Hamas.

Dirar Abu Sisi, 42, operations manager at Gaza’s only power plant, went missing Feb. 19 and resurfaced a few days later in an Israeli jail. His Ukrainian-born wife accused Israel’s overseas intelligence service, Mossad, of abducting him, and he later told court reporters he had been “kidnapped.”

On Monday, Abu Sisi was formally charged with developing rockets fired from the Gaza Strip at Israel, increasing their range and ability to penetrate Israeli armored vehicles, according to a summary of the indictment released by the Israeli Justice Ministry.

The indictment alleged that Abu Sisi had acquired extensive knowledge of rocket technology at a military engineering academy in Ukraine. He was also charged with establishing a military academy in Gaza to train Hamas commanders.

In a brief courtroom appearance, Abu Sisi said he had been seized to gain information about Gilad Shalit, an Israeli soldier held by Hamas, and that the charges against him were fabricated when his interrogation showed he had nothing to do with the captive soldier.

A Hamas spokesman in Gaza denied any links between Abu Sisi and the group, calling the Israeli charges false.