Investigators do not believe Chandra Levy would easily be lured from her apartment by a stranger, Washington's police chief said Sunday.
The former federal intern, last seen April 30, is "a pretty cautious woman and just wasn't one to just throw her door open to anybody if there was a knock at the door and things like that," Chief Charles Ramsey said.
"I mean, it just doesn't fit that it would be a stranger or something like that," Ramsey said on CBS' Face the Nation.
Levy's family believes the 24-year-old from Modesto, Calif., left her apartment to go with someone she knew because she did not take her purse, wallet, identification or credit cards, said lawyer Billy Martin. He represents Levy's parents.
"For some reason, Chandra appears to have been lured, called or brought out of the apartment expecting to return, and lured, brought out with no identification taken with her, and it's suspect," Martin told NBC's Meet the Press.
Police have reported finding no signs of foul play in her apartment.
The missing person's case has generated national attention because Rep. Gary Condit, whose district includes Modesto, acknowledged to investigators that he was having an affair with Levy, a police source has said.
Condit, 53 and married, is not a suspect in Levy's disappearance, police have said. He has kept a public silence, and only acknowledged the romantic relationship on July 6, in his third interview with police, the source said.
That admission prompted the Senate's top Republican, Trent Lott of Mississippi, to say Sunday that Condit should resign. Previously, only Rep. Bob Barr, R-Ga., had suggested publicly that Condit quit.
"Infidelity is always unacceptable, but particularly when you have an elected official involved in a position of trust with a young girl, an intern," Lott said on Fox News Sunday.
"If these allegations are true, obviously he should resign. And if he doesn't, the people of his district probably will not re-elect him," Lott said.
Rep. Christopher Shays, R-Conn., did not agree with Lott. "If infidelity is the test, there'd be a number of members of Congress that should resign," he told CNN's Late Edition.
Messages left for Condit's spokeswoman were not immediately returned Sunday.
Under pressure from the Levy family, Condit took a polygraph test last week at the direction of his lawyer, Abbe Lowell, and without police investigators present.
Investigators will ask Condit to submit to a polygraph test administered by police. Ramsey said he is not hopeful Condit will agree.
"The appropriate thing to do is wait and see what the police say when they've had a chance to evaluate the polygraph the congressman took," said Marina Ein, a spokeswoman for Condit.
Police have not received the results.