BEIRUT, 1 September 2005 — Lebanese authorities questioned yesterday four pro-Syrian generals detained under suspicion in the assassination of former Prime Minister Rafik Hariri, but they freed a fifth suspect overnight.

UN investigators probing the February killing that transformed Lebanon’s political landscape named the suspects on Tuesday and interrogated all five — a top aide to pro-Syrian President Emile Lahoud, three former security chiefs and a former member of Parliament close to Damascus.

The UN team handed them overnight to Lebanese authorities, who kept them at police barracks under heavy guard.

The ex-MP, staunch Syria ally Nasser Qandil, was freed in the early hours while documents detailing the interrogation of the other four men were sent to Lebanese Public Prosecutor Saeed Mirza.

A diplomatic source told Reuters Qandil was still a suspect in the investigation.

Security sources said a magistrate, Judge Elias Eid, was questioning the suspects before he decides whether to issue arrest warrants against them, extend their detention or free them. He has at least 48 hours to rule.

The detentions were widely seen by Lebanon’s media as a breakthrough in investigations, with the UN team implicating for the first time allies of Syria in the bombing that killed Hariri and 20 others in Beirut.

The UN Security Council ordered the probe after a fact-finding mission found Lebanon incapable of carrying out a credible investigation into the attack that hastened the departure of Syrian troops from the country after three decades. It welcomed Tuesday’s detentions and again urged all parties to cooperate with the UN investigator, veteran German prosecutor Detlev Mehlis, and his team.

Damascus denies any role in Hariri’s death and has pledged to work with the inquiry.

Mehlis, who will hold a news conference today to outline the probe’s development, was expected to reveal Syria’s response to his requests of cooperation and the inquiry’s length, a diplomatic source told Reuters.

The Security Council gave the German prosecutor a renewable 3-month mandate to investigate the killing. He began work on May 25. Former MP Qandil said he was freed hours after he handed himself in to the UN team.

“I am always prepared to give all the probe requires in its actions, if the team believes we have something that would benefit the investigation,” Qandil told Reuters.

Lebanese police detained Maj. Gen. Jamil Al-Sayyed, former head of General Security, Maj. Gen. Ali Al-Hajj, ex-chief of police, and Brig. Gen. Raymond Azar, former military intelligence chief, in dawn raids on Tuesday at the request of UN investigators.

Qandil and Brig. Gen. Mustafa Hamdan, the head of Lebanon’s Republican Guard, handed themselves over to the UN team.

Hamdan, a close aide of pro-Syrian Lahoud, was the only security chief to keep his job after parliamentary elections that ended in June ushered in an anti-Syrian majority for the first time since the end of Lebanon’s 1975-1990 civil war.