For 18 years, Luis Alberto Garcia-Perez allegedly assumed the identity of a dead man, going so far as to collect Medicare, get passports, and commit crimes.

Yesterday, “the jig was up,” the sergeant who helped catch him, William Planeta, said.

In 1983, Ismael Camacho Jr. was killed in a triple homicide in the Bronx. He was shot multiple times by a .30 caliber carbine, police said.

Five years later, he applied for a Puerto Rican driver’s license, or so it seemed, Mr. Planeta said. In truth, the applicant was Garcia-Perez, a man of similar height born just 10 months earlier than Camacho. In the ensuing years, Garcia-Perez allegedly used his new identity to get two passports and travel between the Bronx and his native Dominican Republic. He also was convicted on two counts of driving while intoxicated and a felony count of possession of a stolen vehicle identification number, though he never spent time in prison. He had a voter identification card, but it wasn’t clear whether he actually voted, police said.

The pieces came together after Garcia-Perez was arrested in upstate New York. Police there ran his identification, and found two sets of fingerprints for the same person. Officers from the New York Police Department’s Document Fraud unit verified that Garcia-Perez had assumed Camacho’s identity by investigating documents and the headstone where Camacho is buried in the Bronx.

Garcia-Perez faces two federal charges of passport fraud, which each carry a maximum penalty of 10 years in prison. Other charges are pending, and he also faces deportation back to the Dominican Republic.

At first, Garcia-Perez adamantly maintained that he was Camacho, but when he was told the man he was impersonating is dead, he admitted his real identity, Mr. Planeta said.