Law enforcement officials are expected to decide within two weeks whether to bring criminal charges against five university students who were questioned yesterday by a U.S. prosecutor about possible misuse of an Arizona congressman's long distance telephone line.

The students, three from American and two from George Washington universities, were questioned individually by assistant U.S. Attorney John F. Finnegan and Lt. Richard F. Xander, a District of Columbia police official assigned to the Capitol police force.

Meanwhile, it was learned yesterday that Southern Pacific Communications, which provides long distance telephone service at bulk rates to private customers, is investigating reports that American University students wrongfully charged $4,000 worth of calls to the account of a Los Angeles clothing store.

A spokesman at Southern Pacific's Washington area office said yesterday in a telephone interview that "we have the bill" to show the calls were made from the AU campus. A spokesman said that the students somehow had obtained the California company's private authorization code needed to plug into the long distance service.

"We're not looking to cook any kids, we just don't want it to occur again," the spokesman said, adding that "all we want is restitution for the cost of the telephone calls."

Sources said that the five students questioned at the U.S. Attorney's office yesterday told authorities that they were not aware that the long distance line they were using belonged to Rep. Bob Stump [D-Ariz]. The code of digits needed to key into Stump's line was "just common knowledge on campus; it seemed like everybody knows it," one law enforcement official said.

At stump's Capitol Hill office yesterday, the long-distance line that students had monopolized for months appeared to be back in the congressman's control.

"It's nice not to have to battle the students for use of the [long distance] line," said Lisa Jackson, Stump's press secretary.

Several officials said yesterday that news reports last week about misuse of long distance lines prompted a spate of anonymous confessions of students who admitted they had used the long distance lines.

The reports "created havoc among the students" who apparently felt compelled to clear their consciences on a no-name basis, one law enforcement source said.