NEW YORK (CBSNewYork) — Police are investigating the deaths of two next door neighbors were found murdered in Brooklyn.

Investigators removed evidence early Monday from a building at 140 Moore Street after the neighbors were found dead two days apart in separate fifth floor units, both with gunshot wounds.

Residents are stunned.

“Of course they are in shock because this is terrible,” one woman told CBS2’s Natalie Duddridge.

Police say family members discovered 54-year-old Basil Gray just after 4:30 p.m. Sunday in what detectives are calling an apparent homicide.

“Members of the deceased came to check on him because they had not heard from him since Thursday evening. This was unusual,” NYPD Deputy Chief Michael Kemper said Sunday. “Upon arriving, they observed him lying on the floor unconscious.”

The NYPD says Gray was shot in his apartment, 5B, saying they found similarities to the crime scene in 5C. That’s where less than two days before, police said 62-year-old Ana Delvalle was found dead Friday night. Her hands were bound together and she was shot multiple times in the head, Duddridge reported.

“There is similar evidence from today’s apartment that I observed in from Friday’s,” Kemper said.

Sources say one theory police are looking at is that Gray was shot after he checked on Delvalle, perhaps intercepting the killer.

“There’s a strong possibility that he died Friday approximately the same time as the female neighbor,” said Deputy Chief Charles, executive patrol officer of Brooklyn North.

Sources believe Delvalle was the initial victim. Residents say she was active in the community center and they had just taken a picture together the day before she died.

“Used to come to the center,” one resident said. “That’s why I knew her. She was a good person.”

Crime scene investigators did not see any signs of forced entry in either case. They also believe the same gun was used in both murders.

“There was a small amount of U.S. currency, money, from Friday’s incident, a very small amount,” said Kemper. “Not sure if that’s the motive.”

The NYPD has been passing out flyers offering a $1,000 reward for any information leading to an arrest.