The Secret Service yesterday entered an investigation into the alleged theft of patient records from the University of Pennsylvania Health System, the local agent in charge indicated.

The records were used to create bogus credit cards that were used to make nearly $3,000 in purchases at an Upper Darby Sears, according to authorities.

A spokeswoman for the health system said yesterday that 18 medical records had been compromised but that all the victims had been notified and had been offered help repairing their credit issues.

Upper Darby Police Superintendent Michael Chitwood put at 19 the number of copies of individuals' records found in a car being used by Shacoy McNish, 27, of Upper Darby, who was arrested on identity-theft charges Nov. 23 at the Sears at 69th Street.

However, Chitwood said, the Penn employee who allegedly pilfered the records "had access to thousands of files. Allegedly somebody was terminated by the health system" in connection with the case, he said.

Penn Health System spokeswoman Susan Phillips wouldn't say whether anyone had been fired. Penn police are investigating.

Robert Slama, Philadelphia Secret Service agent in charge, confirmed that his agency was investigating "a case with ties to an individual arrested in Upper Darby. We're working closely with University of Pennsylvania authorities," he said but wouldn't comment further.

Chitwood said the medical-record thefts came to light after McNish presented a Sears cashier with a bogus credit card in the name of a woman who supposedly had added him as an "authorized user" of the card.

Chitwood said the clerk became suspicious because McNish had used another woman's card, which also listed him as an authorized user, at the same Sears on Nov. 18.

Neither woman, one from Center City and the other from South Philadelphia, knew McNish, who had no connection to the UPenn Health System, Chitwood said.

Of the records found in the car, owned by a girlfriend of McNish, Chitwood said, "We noticed that all 19 of them were photocopies of what appeared to us to be medical records and the information on all 19 came from the University of Pennsylvania Health System."

Chitwood said the copies included Social Security numbers, date of birth, name and occupation.

Altogether, McNish allegedly bought $2,900 worth of goods from the store in his November visits.