Mohammed Atta checked into this Econo Lodge room on Las Vegas Boulevard on Aug. 13, 2001. Review-Journal Files Mohammed Atta

The intelligence community still is puzzling over why Mohammed Atta and four of his accomplices made several trips to Las Vegas in the months leading up to the Sept. 11, 2001, attacks.

Ellen Knowlton, former head of the FBI's Las Vegas office, said she expects the quest for answers will continue.

"It was pursued as aggressively as humanly possible," said Knowlton, who retired from the FBI in February. "It will never be closed until it's solved."

In its July 2004 report, the 9/11 Commission wrote of the six different trips, "Beyond Las Vegas' reputation for welcoming tourists, we have seen no credible evidence explaining why, on this occasion and others, the operatives flew to or met in Las Vegas."

Adding to the mystery is the fact that all four hijackers who piloted the doomed aircraft spent time near Las Vegas Boulevard.

The lack of definitive answers hasn't kept current and former law enforcement from theorizing about the visits, the last of which took place less than a month before the attacks.

Former Clark County Sheriff Jerry Keller said he thinks the hijackers were eyeing Las Vegas for a possible future attack involving other al-Qaida members.

"We had to be a collateral target or they wouldn't have been here," Keller said.

Grant Ashley, the FBI's special agent in charge in Las Vegas at the time of the attacks, said he has come to view the visits as "planning summits."

Ashley, who left the bureau earlier this year to become vice president of security for Harrah's Entertainment, said the group may have put the finishing touches on the 9/11 plans based on observations they made on first-class flights to Las Vegas.

When the hijackers left Las Vegas, they flew coach to different locations, Ashley said.

Dave Staretz, supervisory special agent for the FBI in Las Vegas, said investigators received more than 3,000 leads concerning the visits and spent weeks canvassing the area around the Strip where the hijackers were known to have been.

But they found no evidence that the hijackers came to Las Vegas to pick up money or meet with associates other than Lotfi Raissi, an Algerian man who was detained after Sept. 11 on suspicion that he helped plan the attacks.

Raissi later was released from custody in England without charge.

Staretz said the hijackers, like other infamous criminals before them, may have felt they easily could blend in here and enjoy the indulgences of America's playground.

"Las Vegas is an international city," Staretz said. "They all come to Vegas at one time or another."

Several dancers at area strip clubs told investigators they remembered seeing the terrorists, though these tips never were substantiated.

Assistant FBI Director John Miller said the hijackers' upcoming mission may have exempted them from some of the normal requirements of fundamentalist Islam.

"If their cover is that they're not religious and needed to blend into Western society then maybe a lap dance was acceptable," Miller said.

REVIEW-JOURNAL