After the alleged fake fireman was spotted yesterday in a Cobble Hill coffee shop purchasing a large cup of regular coffee with milk, police rushed to the Kew Gardens home of Peter Braunstein’s mother to retrieve one of his pillows in the hope that a police dog could pick up his scent.

A bloodhound named Chase sniffed the pillow and seemed to detect Mr. Braunstein’s scent at the coffee shop, Bococa’s Cafe on Court Street. He followed it two blocks before the smell apparently faded, police said.

A bit later, Chase appeared to pick up Mr. Braunstein’s scent a few blocks away from Bococa’s in front of an abandoned building, police said. While law enforcement authorities in the canine unit said police dogs are seldom wrong, police said there were no signs that Mr. Braunstein had been in the building.

Police would not confirm whether the man seen in Brooklyn actually was Mr. Braunstein, 41, who has been on the run since he allegedly posed as a fireman and drugged and molested a Chelsea woman for nearly 13 hours on Halloween. They eventually called off the Brooklyn search, saying it had proved fruitless.

The owner of Bococa’s, John Arena, said he was certain that it was Mr. Braunstein who walked into his restaurant at about 7:30 a.m. and ordered a coffee. He told police officers on patrol in the neighborhood, which instigated the manhunt.

Mr. Braunstein’s mother, Angele Braunstein, 75, told The New York Sun that her son had slept on the white, standard-size pillow three weeks earlier on a cot set up in his bedroom-turned office in her apartment. She had already removed the pillowcase and said she suspected her fingerprints might be all over the pillow.

Ms. Braunstein downplayed the search, saying, “They spot him everywhere.” Police have received numerous tips from people claiming to have spotted Mr. Braunstein, but none has resulted in his capture. November 2 was the last day investigators confirmed a sighting of Mr. Braunstein. That day, he used a MetroCard paid for with a credit card.

Ms. Braunstein did confirm that her son drank large cups of regular coffee with milk in the morning. And the Brooklyn locale would not have been a random stop for Mr. Braunstein, because his ex-wife lived nearby, police said. Ms. Braunstein also said a one-time best friend of her son’s lived in the borough. But the suspect’s mother said Mr. Braunstein maintained no relationships with friends. “He cut off with all his friends a long time ago,” she said.

Ms. Braunstein said her son has suffered from mental illness, taking Prozac at one point to treat his depression and overdosing last year in what may have been a suicide attempt. While he has long wrestled with his depression, Ms. Braunstein said it was when he was fired from his writing job at Women’s Wear Daily in 2002 that Mr. Braunstein lost it.

Mr. Braunstein’s mother also said her son suffered from a deep-seated anger problem, which drove him into therapy for a couple of sessions when he was in his 20s.

“I think he is out of his mind,” Ms. Braunstein said.

Mr. Braunstein pleaded guilty in the summer to menacing his ex-girlfriend.

Mr. Braunstein, a freelance writer, was living with his mother for one and a half years before the alleged Halloween attack, his mother said. For the 20 years prior, she said she saw her son only when they met in restaurants. Mr. Braunstein has been estranged from his father, Alberto Braunstein, who lives on the East Side.

Ms. Braunstein expressed disappointment with how her son’s life has turned out. “He could have been a light. He could have awoken the world to something,” she said.

Ms. Braunstein said she did not know if her son committed the Halloween crime, or at least all the acts involved in it.

“Because the crime is so extensive, they say, I can’t believe it. I don’t believe he did all that crime,” Ms. Braunstein said. Either way, she hopes police capture him so he can get psychiatric help.