Square-strollers beware: The Harvard police issued a warning yesterday to all members of the University community about con artists who may try to swindle you out of thousands of dollars.

The money filchers have already bilked one Kennedy School affiliate out of $5,000, police said. The unidentified crooks have plucked thousands of dollars from at least five Cambridge residents in the last four weeks.

In what police call one of the oldest con games in history, one con artist typically approaches a person on the street and tells him or her that he has found a wallet full of cash and checks.

The crooks then propose cashing the check and splitting the proceeds, but they first ask for money from the victim as a show of good faith.

Criminals employing this same con game preyed on several Asian-American female Harvard students in April 1993. Two suspects were arrested in connection with those scams, and police say they do not know if there is a connection between the 1993 crimes and the recent incidents.

"We want to alert the community and ask for their cooperation in apprehending these suspects," said Harvard police Lt. John F. Rooney.

"These people have a great gift of gab and may just encounter you on the street," Rooney said. "If you're encountered, please call the Harvard police right away."

Rooney said that victims so far have been able to provide police with only vague descriptions of the suspects. They usually work in groups of men and women, he said, and employ three or four different scams.

In addition to promising to cash a fake check, the suspects may also produce a bogus money-roll--a wad of paper with a few real bills wrapped around the outside.

He said that anyone who is approached should note license plate numbers or other identifying information that could aid police.

"This crime is becoming much more commonplace, and we really want to get the word out that people need to be aware of this," Rooney said.

Anyone with information about the case should call Harvard police at 495-1212, Rooney said