BAGHDAD, Iraq (AP) -- An American who was beheaded by militants had told friends he was arrested by Iraqi police in Mosul because he had an Israeli stamp in his passport. The Mosul police chief Thursday denied having arrested him.

The body of Nicholas Berg, 26, was found last weekend in western Baghdad. Three days later, a videotape posted on an al-Qaida-related Web site showed Berg decapitated by hooded, armed men.

Questions about Berg's stay in Iraq remain, including the time and place of his abduction. U.S. and Iraqi officials have offered varying accounts of their contacts with the self-employed telecommunications businessman from West Chester, Pa., a Philadelphia suburb.

U.S. officials said Wednesday that Iraqi police arrested Berg in Mosul on March 24 because they believed he may have been involved in "suspicious activities."

U.S. spokesman Dan Senor would not explain those suspicions but insisted that Berg was held by Iraqi -- and not American -- authorities. He said, however, that the FBI visited Berg three times before he was released April 6.

In e-mails released by his family, Berg wrote about his experiences in trying to track down and later meeting an in-law in the Mosul area. Berg also described his work in seeking to repair communications towers in Iraq.

In Mosul, police chief Maj. Gen. Mohammed Khair al-Barhawi insisted his department had never arrested Berg and maintained he had no knowledge of the case.

"The Iraqi police never arrested the slain American," al-Barhawi told reporters. "Take it from me ... that such reports are baseless."

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A U.S. official, speaking on condition of anonymity, said Berg was detained by Iraqi authorities "for his own protection" because his behavior in Mosul seemed unusual for a Westerner.

He had been seen traveling in taxis and moving about the dangerous city without any escort, the official said. He added that Berg, who was Jewish, had in his possession texts that were "anti-Semitic" in tone, the official said without elaborating.

In his e-mail quoted by the Times, Berg guessed the FBI agents in Mosul had questioned him about Iran because he was carrying some literature in Farsi and a book about Iran.

He also wrote that U.S. military police who were supervising the Iraqi police had heard some of his fellow prisoners referring to him as an Israeli and suggested he be moved to a separate cell.