(Montgomery County Police Dept.)

The father of two, asleep next to his wife in their suburban-Washington home, was awakened by a cellphone beep. It signaled a message from his Nest outdoor security system.

“Nest has spotted a person,” it read.

He pushed a few buttons, rewinding the recorded video. There was a person all right, and he had no clothes on.

“I couldn’t believe it,” the homeowner recalled Friday. “I thought it was a bad dream.”

Montgomery County detectives said the naked man tried unsuccessfully to get into the home — in Bethesda, just after midnight May 17 — before a motion light activated and sent him running into the darkness.

On Friday, police released the driveway video footage, as well as footage of the attempted break-in recorded from inside the home looking out through a glass door.

Detectives said they hope someone will recognize the naked man and call with information.

“We don’t know who the suspect is,” said Sgt. Rebecca Innocenti, a police spokeswoman.

Nor do police know what his intentions were.

The driveway video footage, blurred for public release right around the man’s midsection, shows him approaching the house, veering right at a parked Audi, walking around a large trash can, turning around and exiting stage left. The interior camera — trained at glass doors in a walkout basement — shows the man jiggling a door knob and peering in. He walks a bit to his right. Then the motion light flashes, and he scampers.

In an interview Friday, the homeowner asked that he not be named, owing to concerns about safety because the man remains at large, and concerns that his identity would increase the chances his two children would find out what happened. The boy and girl are younger than 10, and their parents are trying not to tell them about the naked, near intruder.

“He had some odd behavior,” said the homeowner, who works for a software company. “It’s not quite clear what he was up to.”

His home has six cameras inside and outside, linked by sophisticated machine-learning software, running in Cloud computing, which uses algorithms to examine video images — trying to sift through shots of blowing leaves and small animals before issuing alerts about humans.

“I’m a bit of a home-automation junkie,” the owner said.

The night he received the cellphone beep and watched the naked man on the outdoor recording, he woke up his wife and showed her the video.

“It must be a drunk college kid,” she said.

The homeowner went downstairs, looked out the windows, saw nothing amiss and went back to sleep. After waking, he looked at the footage from an interior camera — and saw the apparent, attempted break-in. “We got much more concerned,” he said.

He called police. He shared the video on his neighborhood list-serve.

The homeowner said he does not know whether the man was a peeping Tom, was impaired or was trying to break in. “Maybe it was a combination of all those things,” he said.

Thinking back on what he saw on the video, he expressed a worry that if the man was willing to wander around his yard, he might have been willing to quietly wander around in the house and get to his children’s bedrooms.

But there was one comforting aspect: “We know he wasn’t armed.”

Police asked anyone with information about the case to call 240-773-6710 or 866-411-TIPS (8477).