NEW YORK (CBSNewYork) — In a drug case with a twist, prosecutors say an alleged Brooklyn cocaine dealer had a profitable sideline scamming senior citizens.

As CBS2’s Tony Aiello reported, it started for the city’s Special Narcotics prosecutor as a fairly routine case involving a kilo of cocaine.

But after the arrest of suspect Ricardo Castang, prosecutors kept digging through cellphone and bank account records.

“We saw some very odd deposits from people all over the U.S. — 17 different states,” said Special Narcotics Prosecutor Bridget Brennan.

The states included New York, New Jersey, Pennsylvania, and Connecticut.

“Castang was running a scam where elderly victims ended up being targeted,” Brennan said.

Brennan said Castang called seniors, convinced them that they had won the Publisher’s Clearing House sweepstakes, and conned them into sending him checks to cover taxes and fees.

He allegedly raked in about $300,000 in the space of a year.

“People are told suddenly out of the blue that they won a whole lot of money, and I think they were probably just very excited by it,” Brennan said.

Investigators said Castang’s scam was so successful that he grew either overconfident or maybe a little sloppy – allegedly having victims send checks in his name to his address in Brownsville, Brooklyn.

Residents on Lincoln Place remember Castang as a quiet man of seemingly modest means. They were stunned to learn that he allegedly scammed two dozen seniors – one of them 91 years old.

“Come on! That’s somebody’s grandmother you’re scamming,” said Eric Brunt of Brownsville. “That’s somebody’s grandmother; that’s somebody’s mother you’re scamming.”

Investigators believe there are more victims out there, and urge them to come forward.