PRAGUE (AP) — The mystery behind a booby-trapped safe that exploded and killed the Palestinian ambassador has kept investigators working around the clock Thursday.

As the probe deepened, more unanswered questions arose over conflicting statements coming from Palestinian officials — namely, was the former Palestinian Liberation Organization safe in constant use at the Prague embassy, and if so, what made it explode?

Ambassador Jamal al-Jamal, 56, died Wednesday of massive injuries from the blast. The career diplomat had only started his posting in October.

Police spokeswoman Andrea Zoulova said it appeared that the door of the safe had been booby-trapped, but it was unclear how al-Jamal tried to open it or what type of safe it was. It was also unclear what caused the safe to explode.

Zoulova told The Associated Press on Thursday that nothing had been found to suggest the diplomat had been a victim of a crime, but she declined to elaborate.

Weapons, however, were found and were considered illegal because they were not registered, Zoulova said. It was unclear what type of weapons were found at the complex.

The country's counterintelligence service, BIS, said the death didn't appear suspicious. Prime Minister Jiri Rusnok called the death "an unfortunate and tragic event."

Palestinian Foreign Minister Riad Malki also said no foul play was suspected.

Malki, however, said Wednesday the safe had been left untouched for more than 20 years and that the ambassador opened it to see what it contained. But Palestinian Embassy spokesman Nabil El-Fahel told Czech radio Thursday it had been in constant use.

"(The safe) was used on a daily basis at the embassy and it was opened and closed almost every day," he said.

The safe was recently moved from the old embassy building, but it had come from a building that used to house the PLO's offices in the 1980s, Malki said.

The PLO had offices in Prague in 1976 but it obtained diplomatic status in 1983 when it was officially recognized.

During the Cold War — before the fall of the Soviet Union — the PLO had close ties with the Eastern bloc countries.

Several members of the PLO were linked to terror attacks during the Cold War.

Pavel Kolar, the head of Prague's Institute of Criminology, said Thursday that their investigation would take several days at least.

The death was being investigated as a case of negligence and possession of illegal armaments.

The embassy recently moved to a new complex, and the safe was in the ambassador's residence.

A team of Palestinian experts is expected to participate in the investigation.

Security analyst Andor Sandor said it would be unusual to protect embassy documents with a booby-trapped device.

During their search, police discovered one more safe at the embassy complex but no explosives were found.