Montgomery County police are searching for at least one additional suspect in a credit card scam that targeted more than 100 customers of the Broadway Diner in Rockville and that may have also victimized patrons of a nearby hotel, investigators said yesterday.

At least four customers of the Bethesda North Marriott Hotel on Marinelli Road may have been victims of credit card fraud as part of the nine-month scheme, police said.

"We believe that there are other people involved" in perpetrating the fraud, Detective David Hill said.

On Tuesday, police announced that they had charged Adou Kouao, a former waiter at the Broadway Diner, and Donald Vias, who police said acted as Kouao's accomplice. Hill said the theft at least four credit card numbers at the Marriott appear to be related. He did not comment on whether police have determined the identity of the third suspect.

According to investigators, the scheme began in November, when Kouao, 24, of Silver Spring, began "skimming" the credit cards of Broadway Diner customers, using a hand-held device that extracts information from a credit card's magnetic strip. The credit card numbers were then transferred to counterfeit cards and used to buy thousands of dollars' worth of electronics.

The skimmer "is the kind of thing that would not draw any attention and could be concealed in a man's pocket," said Montgomery Assistant State's Attorney Robert Hill.

Kouao, 24, and Vias, 21, made fraudulent purchases amounting to at least $10,000, police said in charging documents filed in Montgomery District Court. David Hill said yesterday that some of the equipment was sold for cash.

Vias fraudulently purchased at least 14 Apple iPods, eight Sony PlayStation Portables, a computer printer and a Sony PlayStation 2 from stores in Bethesda and Germantown, according to court papers.

Kouao used proceeds from the stolen goods to purchase a 1997 Land Rover SUV, the detective said.

Robert Greenberg, a lawyer representing Kouao, declined to comment yesterday on the charges. It could not be determined whether Vias had obtained a lawyer.

The scam began to unravel in May, when two customers at a Target store in Germantown tried to use a credit card to buy a $400 DVD player and two $500 gift cards. The credit card, which was maxed out, was declined. So they tried another card, which was also declined. After the third and fourth credit cards, store employees got suspicious and called police.

David Hill discovered several similar instances of suspicious purchases across the Washington region, and Kouao became a suspect when it grew apparent that most of the stolen credit cards had been used for purchases at the Broadway Diner.

The detective said that "a little over 30" diner customers have been confirmed as victims. According to charging documents, Kouao told police in a statement that he stole the credit card numbers of "at least 100 customers."

Management at the diner, where Kouao worked for four years, was not aware of his activities and was not involved in the scheme, police said.

Kouao was charged June 27 with several counts of credit card fraud and three counts of theft. He posted $30,000 bond and was released from the Montgomery County jail June 29, authorities said. Vias, charged with 10 counts of credit card fraud and four counts of theft, was released Tuesday night on $10,000 personal bond, police said.

Adou Kouao, left, stole card data from customers at a Rockville diner, aided by Donald Vias, police say.