A Black September terrorist who served only about half his 30-year sentence for planting three car bombs in New York City in 1973 was released Thursday into the custody of immigration officials to be deported.

Khalid Al-Jawary, 63, was released from the Supermax maximum-security prison in Florence, Colorado, said Carl Rusnok, a U.S. Immigration and Customs Enforcement spokesman. Rusnok said a federal immigration judge had signed a deportation order for Al-Jawary.

Al-Jawary's release date was set for Thursday after he was credited with time served before his sentencing and good behavior.

Rusnok declined to say where Al-Jawary was being held as he awaits deportation. It's also not clear when Al-Jawary will be deported or where he will be sent. The mysterious terrorist had many aliases and was known to use fake passports from Jordan, Iraq and France.

Al-Jawary has denied involvement in the 1973 New York City bomb plot; he claims his real name is Khaled Mohammed El-Jassem. The FBI to this day remains unsure of his true identity; his nom de guerre was Abu Walid al-Iraqi.

Al-Jawary, under that name, was convicted in 1993 of placing two powerful bombs along Fifth Avenue and a third at John F. Kennedy International Airport 20 years before. The bombs, which failed to detonate, were timed to coincide with the arrival of then-Israeli Prime Minister Golda Meir.

The case has drawn widespread attention since an Associated Press investigation last month raised questions about whether Al-Jawary had a role in a murderous letter-bombing campaign and the bombing of an TWA flight in 1974 that killed 88 people.

Al-Jawary was a member of Black September, a terrorist group responsible for many lethal attacks, including the killings of 11 Israeli athletes at the 1972 Olympics in Munich, Germany.

In 1979, Al-Jawary was arrested in Germany while trying to carry out a terrorist attack on likely Israeli and Jewish targets. The next year, he escaped an assassination attempt in Beirut that left two of his aides injured and his car smoldering.

Al-Jawary blamed the attack on Mossad, Israel's foreign intelligence service. At the time of the failed hit, he was working for Abu Iyad, a top commander in Fatah, the Palestine Liberation Organization's military wing.

Iyad was killed in Tunisia by a rival Palestinian faction in 1991. Al-Jawary was apprehended passing through Rome in January 1991 to attend Iyad's funeral. Iyad was believed to have helped plan the Munich murders.

Retired FBI agents John Syron and Jim Phelan, who worked the case in 1973, said freeing Al-Jawary was a mistake. The bombs would have killed many people if they had gone off, they said.

"Bad move," Phelan said. He's not going to change.

Authorities said Al-Jawary's family lives in the Middle East but declined to say where.

Before his transfer to ICE custody, Al-Jawary was being held at the Supermax, considered the United States' most secure federal prison. It's home to other notorious terrorists including Sept. 11 conspirator Zacarias Moussaoui and Ramzi Yousef, who masterminded the 1993 World Trade Center attack.