A Brooklyn financier was found naked and dead in his tony Dumbo pad — after a gay bondage hookup went awry, police sources said Tuesday.

Neil Rodney Smith, 57, CEO of the investment firm Infraccess, was discovered lying on his back in bed with a wet towel stuffed in his mouth and a pillow over his face inside the apartment at 1 Main St. around 1:45 p.m. Monday, police sources said.

“He went online and hooked up with some guy and, whatever they were doing,” he died, a police source said.

Not long before his death, “A roommate heard a guy in there with him. He heard them having sex,” the source added.

Sounds from the room stopped, and a roommate later found Smith dead, the police source said.

There were no signs of trauma — but police are investigating whether there may have been foul play, according to cops.

Police also are reviewing surveillance camera footage of a male visitor from outside the home.

“There is video surveillance of a guy and a girl outside the apartment. The girl stays out, and the guy goes in,” the police source said.

Smith had been talking online with the mystery man before he was found dead, according to cops.

“There were text messages exchanged and Facebook stuff where he’s hooking up with this guy,” a police source said.

Police are also looking into whether the male visitor was a prostitute, according to cops.

Additional reporting by Natalie O’Neill and Jennifer Bain