Updated

U.S. authorities said Wednesday a young American who was beheaded by militants had been warned by the FBI to leave Iraq (search) and was offered a plane ride to safety at a time when a new wave of violence spread across the country, making road travel extremely dangerous.

Mystery surrounded not only Nicholas Berg's (search) disappearance but also why he had been held by Iraqi police for about two weeks and questioned by FBI agents three times. Berg's family disputed U.S. officials' claims that Berg was never in U.S. custody.

"The Iraqi police do not tell the FBI what to do, the FBI tells the Iraqi police what to do. Who do they think they're kidding?" Berg's father, Michael, told The Associated Press from his home in West Chester, Pa., a Philadelphia suburb.

Berg was last in contact with U.S. officials in Baghdad on April 10, and his body was found Saturday in Baghdad. Staff members at the $30-a-night Al-Fanar Hotel in Baghdad (search) told the AP that Berg stayed there for several days until April 10.

Two e-mails sent by Berg to his family and friends show the 26-year-old telecommunications expert traveled widely and unguarded throughout Iraq -- an unsafe practice rarely done by Westerners.

The FBI (search) warned Berg shortly before his disappearance that Iraq was too volatile a place for unprotected American civilians but he turned down a State Department offer to fly him home, U.S. officials said Wednesday.

Michael Berg said his son refused a U.S. offer in early April to board an outbound charter jet because he believed travel to the airport was too dangerous. American soldiers refer to the airport highway as "RPG Alley" because of frequent attacks by insurgents firing rocket-propelled grenades.

According to the State Department, Berg told an American diplomat in Baghdad that he preferred to travel on his own to Kuwait.

"At that time, the U.S. consular officer extended an offer to assist Mr. Berg to depart Iraq by plane to Jordan," said State Department spokeswoman Kelly Shannon. "We'd already discussed that possibility with his family, and we mentioned that to him, obviously, when we talked to him on the 10th."

His family said Berg had already intended to leave the country on March 30 but that his detention prevented him from doing so.

Berg first worked in Iraq in December and January and returned in March. He was inspecting communications facilities, some of which were destroyed in the war or by looters.

During his time in Iraq, he struggled with the Arabic language and worked at night on a tower in Abu Ghraib, a site of repeated attacks on U.S. convoys and the location of the notorious prison where U.S. soldiers abused Iraqi inmates.

Michael Berg told the AP that Nicholas' paternal aunt, now dead, married an Iraqi man named Mudafer, who became close to Nicholas. In one of the e-mails, Nicholas Berg describes going to the northern city of Mosul, where he introduced himself to Mudafer's brother, identified as Moffak Mustaffa.

"We got along splendidly," Berg wrote. "We spent a few hours and I helped him establish an e-mail account."

Berg notes that "my presence ... made him more concerned (about his own safety and probably mine too) than I've been the entire time I've been here."

The young man was beheaded on a video posted Tuesday on a Web site. It bore the title "Abu Musab al-Zarqawi shown slaughtering an American," referring to an associate of Usama bin Laden believed behind a wave of homicide bombings in Iraq.

In Washington, Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said it was likely that al-Zarqawi himself was "the lead perpetrator." Al-Zarqawi, a Jordanian, is wanted in the killing of an American diplomat in Jordan in 2002 and is suspected of ordering many homicide bombings in Iraq.

U.S. spokesmen Dan Senor and Brig. Gen. Mark Kimmitt were quick to offer statements of condolence to his family and to draw attention to the barbarity of his death. Senor also said that "to my knowledge" Berg was not affiliated with any U.S. or coalition organization, nor was he ever in U.S. custody.

However, Senor said Iraqi police arrested Berg in Mosul on March 24 because local authorities believed he may have been involved in "suspicious activities."

Senor refused to say more, citing the sensitivity of the case. But he did confirm that the Americans were aware Berg was in custody.

"U.S. authorities were notified," he said. "The FBI visited Mr. Berg on three occasions and determined that he was not involved with any criminal or terrorist activity."

In a statement, the FBI said that its agents "encouraged him to accept [the] ... offer to facilitate his safe passage out of Iraq. Mr. Berg refused these offers."

Berg was released April 6 and checked into the Baghdad hotel.

Senor referred questions about the reason for Berg's detention to the Iraqi police. In Mosul, however, police told the AP they had no knowledge of the Berg case. Police official Safwan Talal said the only American arrested there in recent months was a woman who was released soon afterward.

Since Iraq remains under U.S. military occupation, it seems unlikely that the Iraqi police would have held Berg, or any other American, for such a length of time without at least the tacit approval of U.S. authorities.

Berg told his family that U.S. officials took custody of him soon after his arrest and he was not allowed to make phone calls or contact a lawyer, his father said.

Kimmitt said U.S. forces kept tabs on Berg during his confinement to make sure he was being fed and properly treated because "he was an American citizen."

But the three FBI visits suggest American authorities were concerned about more than Berg's well-being. They may have had their own suspicions about what the young American was doing in Iraq.

During a briefing Wednesday, Senor confirmed that Berg had registered with the U.S. Consulate in Baghdad but insisted he "was not a U.S. government employee, he has no affiliation with the coalition and to our knowledge he has no affiliation with any Coalition Provisional Authority contractor."

He also stated that Berg "was at no time under the jurisdiction or detention of coalition forces."

However, in a Jan. 18 e-mail, Berg said his company had been announced as an approved subcontractor for a broadcast consortium awarded a contract for the U.S.-controlled Iraqi Media Network.

"Practically, this means we should be involved with quite a bit of tower work as part of the reconstruction, repair and new construction of the Iraqi Media Network," he wrote, referring to the network as "something like NPR in the U.S."

It was unclear whether the contract was revoked.

FBI agents visited Berg's parents March 31 and told the family they were trying to confirm their son's identity.

On April 5, the Bergs sued the government in federal court in Philadelphia, contending that their son was being held illegally. In a writ filed April 5 in U.S. District Court in Philadelphia, the Bergs said the State Department told them their son "is currently detained in Mosul, Iraq, by the United States military" and that American diplomats "no longer" had "any authority or power to intervene" on his behalf.

Berg was released the day after the suit was filed. His family said he told them he had not been mistreated. They did not hear from him after April 9 -- when violence flared in Iraq because of the U.S. Marine siege of Fallujah and a Shiite uprising in the south.

Several days later, however, diplomats received an e-mail from Berg's family that "noted he had not been in contact," Shannon said.

On April 14, the consulate sent a private contractor to the Al-Fanar Hotel in Baghdad, where Berg was believed to be staying, to see if he was still there.

"The people we talked to at the hotel didn't remember him being there," Shannon said.

Diplomats then alerted the U.S. military to be on the lookout for him.

But hotel staffers, speaking on condition of anonymity, said Berg stayed in room 602 from April 6 until April 10. One of them said Berg lived in the same room during an earlier visit, which the employee could not remember.

An employee described Berg as a "nice guy" who "always smiled and said hello," unlike other foreign guests. "Once he told me, 'I'd like to learn Arabic."'

"He was very sportive -- had muscles -- and liked the Internet," another hotel worker recalled. "He usually left the hotel in the morning and returned late, around 10 p.m., usually carrying a sack of beer and mineral water."