An American businessman who was beheaded recently in Iraq was visited by FBI agents while he was being held in an Iraqi jail in late March and early April, and he remained in detention for nearly two weeks even though agents eventually recommended that he be freed, U.S. officials said Wednesday.

Nicholas Berg, 26, of West Chester, Pa., vanished after he left his Baghdad hotel on April 10, four days after his release by Iraqi police in the northern city of Mosul. His body was found near Baghdad on Saturday, and his death became public Tuesday when a video depicting his decapitation by Islamic militants appeared on the Internet.

In a pleading filed in U.S. District Court in Philadelphia last month, Berg's parents contended that his incarceration, which began with his detention on March 24, prevented him from returning to the United States on a flight that was to have arrived in New York on March 30.

As arrangements were made instead to fly Berg's remains to Kuwait and then to Dover Air Force Base in Delaware, important questions about his death remained unanswered, including why he was detained for nearly two weeks, and how and when he was abducted and killed.

The Internet display of Berg's slaying and the gruesome disposal of his body constituted one of the most brutal examples in a wave of killings and kidnappings of foreigners in Iraq. An independent businessman, Berg came to Iraq seeking to help repair communications towers and had no affiliation with the U.S. government, officials said.

In Washington, President Bush said there was "no justification for the brutal execution of Nicholas Berg, no justification whatsoever. The actions of the terrorists who executed this man remind us of the nature of the few people who want to stop the advance of freedom in Iraq. . . . We will complete our mission, we will complete our task."

The video attributed responsibility for the killing to Abu Musab Zarqawi, a Jordanian accused of organizing attacks against occupation forces in Iraq. U.S. officials say he has ties to al Qaeda.

A U.S. official in Baghdad said Wednesday that soldiers from the Army's 1st Cavalry Division on a routine patrol found Berg's headless body at 5:30 p.m. Saturday, hanging from a highway overpass a few miles east of Baghdad International Airport. His head lay on the ground nearby, said the official, who spoke on condition of anonymity because of the sensitivity of the case.

Berg's parents contend that because he was detained by the Iraqi police, one of several security agencies established by U.S.-led occupation authority, the U.S. military effectively had custody of him and was holding him without cause. On Wednesday, U.S. officials denied that the military held Berg but acknowledged that FBI agents interviewed him three times during his detention before concluding he was not a threat.

A spokesman for the U.S.-led occupation authority, Daniel Senor, offered little information about the case. "I'm reluctant to release any details at this point," he said. "The U.S. government is committed to a very thorough and robust investigation to get to the bottom of this."

The FBI and the Army's Criminal Investigation Division are involved in the case, and Senor said a decision would soon be announced about which agency would lead the investigation. Federal statutes allow the FBI to investigate terrorist killings of U.S. citizens overseas.

In interviews here, two friends who saw Berg after he was released from detention said he told them he had been arrested at a checkpoint in Mosul when Iraqi police examined his U.S. passport and noticed an Israeli stamp. Travel documents indicating an individual has been in Israel have long sparked suspicion in the Middle East; many Arab countries routinely refuse entry to travelers whose passports bear stamps from Israel.

"He said, 'You want to hear an interesting story? They thought I was a spy because I had a Jewish last name and had an Israeli stamp in my passport,' " said Hugo Infante, 31, a Chilean freelance journalist. "He wasn't [upset]. It was like an adventure for him."

Aziz Taee, 40, an Iraqi business associate of Berg's who has lived in the Philadelphia area for most of the past 20 years, said Berg "was in a taxicab after midnight, stopped during a routine check. The police saw in his passport the Israeli stamp."

On a trip to Iraq in December, Berg flew to Tel Aviv and then Amman, Jordan, before driving overland to Baghdad, his mother, Suzanne Berg, said in a telephone interview.

Suzanne Berg said her son never mentioned an Israeli stamp as a reason for his arrest. "He wrote us an e-mail about his detention and said it was because he was an American out late and it was unusual," she said. "That's the first I heard anything about that."

After Berg's arrest, the occupation authority asked the FBI to find out what he was doing "wandering around in a dangerous area," said Ed Cogswell, an FBI spokesman in Washington.

"This was something of an anomaly," Cogswell said. "We wanted to clarify what he was doing. He said he was there for commercial ventures, and that proved to be the case."

FBI agents interviewed Berg on March 25, March 26 and in early April, and the bureau ran background checks to determine whether he had a criminal record or any known connections to terrorist groups, Cogswell said. He said there was no particular suspicion of wrongdoing by Berg.

On April 5, Suzanne Berg and her husband, Michael Berg, filed a petition for a writ of habeas corpus in Philadelphia, claiming that the U.S. military had illegally detained their son despite an FBI recommendation that he be released. On April 6, Berg was freed.

The FBI said in a statement that FBI agents and officials with the Coalition Provisional Authority "emphasized to him the dangerous environment that exists in Iraq, and encouraged him to accept CPA's offer to facilitate his safe passage out of Iraq. Mr. Berg refused these offers. The CPA coordinated with the Iraqi police for Mr. Berg's release."

After Berg was released, "we recommended that he leave the area, but there's nothing we could do to force him to leave," Cogswell said.

The last known contact with Berg was April 10, when a U.S. consular officer in Baghdad called him and offered to help him arrange a flight to Amman.

"Mr. Berg informed the consular officer that he planned to travel overland to Kuwait instead and would contact his family when he arrived," said Kelly Shannon, a spokeswoman for the State Department's Bureau of Consular Affairs in Washington.

The consular officer informed the family of his decision by e-mail on April 13, and then learned that Berg had not arrived home, Shannon said. On April 14, a consultant was sent to the Al-Fanar Hotel, an eight-story building on the east bank of the Tigris River where, according to the hotel's records, Berg stayed from March 22 to 23 and again from April 6 to 10.

In Room 602, he left behind six sticks of beef jerky, two pairs of 33- and 11-pound weights, a barbell and a pull-up bar. The hotel staff also found a large blue short-sleeve work shirt, a pair of size-46 jeans and four paperback books -- popular fiction by Jon Burmeister, Tom Clancy, Tony Hillerman and Steve Martin.

Those items were strewn about in a hotel storage room on Wednesday. A front-desk clerk, Louai Muhammad, said no American investigators had come to the hotel to ask questions or investigate the death.

The Al-Fanar Hotel is frequented by foreigners, many of them self-employed or small business owners. The guests remembered Berg, who was athletic and strongly built, as a cheerful and gregarious character who could often be found at the $3-an-hour Internet terminals in the hotel lobby.

Tom Popyk, a Canadian freelance radio reporter, remembered the last time he saw Berg. "It seemed like he was tired more than anything else," Popyk said. "He seemed like a typical guy waiting to go home."

Staff writers Ariana Eunjung Cha and Dan Eggen in Washington contributed to this report.

Michael Berg, left, speaks with Carl Goldstein, a funeral director, a day after a video was shown on the Internet depicting the decapitation of his son, Nicholas Berg, in Iraq.