A severely decomposed dead body was found inside a Gowanus apartment building that’s under construction.

Police say they were called to an apartment building on 13th Street and Fourth Avenue after construction workers in the area reported highly decomposed human remains on the third floor.

Neighbors say they believe the body belonged to a relative of the former owner of the building.

“We started smelling something really bad three years ago, and it felt like a dead body, but nobody really knew what it was," says Nana Agyakum, who has lived next door for six years.

Neighbors add the building has had a reputation for being messy, with Department of Building complaints of debris piled outside dating back to 2000.

Police have not identified the body yet, and the medical examiner is still determining the cause of death.