A former Lebanese lawmaker questioned in the assassination of former Prime Minister Rafik Hariri (search) was released early Wednesday. Investigators were expected to keep interrogating four detained pro-Syrian generals over the slaying.

U.N. investigators leading the probe, aided by Lebanese forensic experts, also visited two Beirut (search) residential apartments on Wednesday possibly used by those who planned the massive Feb. 14 bombing that killed Hariri and 20 others, said a security official who asked not to be identified because of the sensitivity of the case.

Legislator Nasser Qandil (search), a staunch defender of Syria's influence in Lebanon, surrendered Tuesday at the request of U.N. investigators probing the killing. He was released early Wednesday but refused to comment on the probe.

"I don't want to talk about this issue," Qandil told The Associated Press. "The information I gave (the investigators) belongs to the probe."

But a newspaper and television station owned by the Hariri family reported the five were wanted for questioning in connection with a letter Qandil allegedly sent to Syrian leaders, explaining the reasons for getting rid of Hariri.

"(Hariri) was heading for winning a guaranteed majority in parliament that would lead to the withdrawal of the Syrian army from Lebanon," Al-Mustaqbal newspaper and the Future Television quoted the alleged letter as saying.

The newspaper also alleged that the four Lebanese generals had held meetings to prepare for Hariri's assassination and that they inspected the bomb scene on the eve of the attack.

Qandil also declined to comment on the media reports.

The detentions were the first major break in the crime that transformed Lebanon after decades of Syrian control. It also followed the United Nations' naming of Qandil and four pro-Syrian generals — including a close ally of Lebanese President Emile Lahoud — as suspects in Hariri's killing.

The generals spent the night at an eastern Beirut police headquarters, another senior Lebanese security official said on condition of anonymity because he was unauthorized to speak to the media.

U.N. chief investigator Detlev Mehlis sent the generals' files to Lebanese investigating magistrate Elias Eid, said the official. Eid will later decide either to release them, free them on bail, or issue arrest warrants.

U.N. investigators also inspected two apartments in an area south of Beirut and took fingerprints before police detained at least four people for questioning, said a security official.

Lahoud stressed the need for the U.N. commission to uncover the truth about the murder.

"Everybody wanted to know the whole truth based on facts and irrefutable evidence, a truth that would identify and uncover those who masterminded the heinous crime, executed it and supported it," Lahoud said in a statement.

Mehlis is expected to submit a report about his findings in the Hariri inquiry to the U.N. Security Council in mid-September, when his three-month mandate ends, unless he seeks an extension.

Hariri's death sparked mass protests that led to the April withdrawal of thousands of Syrian forces from Lebanon and the ouster of Lebanon's pro-Syrian government. Many Lebanese blamed Syria and its Lebanese allies, particularly members of this country's security apparatus, for the assassination. Both sides have denied such claims.