A Manhattan financial analyst went undercover to find out what was happening to her underwear — and nabbed her apartment building’s super by using a hidden smartphone camera to record him sneaking into her pad and then sniffing and swiping her lingerie.

Disturbing surveillance video captured via an iPhone app allegedly shows José Cedillo, 32, furtively enter Ashley Chase’s East 55th Street apartment on Sept. 4 and flip on the lights.

After disappearing from view for about six minutes, Cedillo reappears — holding a pair of Chase’s Victoria’s Secret underwear to his face and taking a deep whiff, she says.

“I don’t want to think what he was doing, but everyone has theories — and I’m sure not good,” Chase told The Post.

Chase first suspected something strange was happening inside her $1,875-a-month, fifth-floor studio when she returned from a Labor Day trip to the Hamptons last year and couldn’t find a purple lace bra.

As time passed, a series of undergarments disappeared, including a black-and-gold bikini top, a tan bra and at least three pairs of panties.

“I also realized at that point that underwear I had worn that weekend that were in the dirty hamper were missing,” she said, describing the moment in July when she put the pieces together.

Figuring it was an inside job, Chase borrowed an old iPhone from her sister and installed an app called Presence, which automatically activates the phone’s video camera whenever it detects motion. She then hid the phone on an end table with a view of the front door.

On Sept. 4, she was headed to Montauk for the Labor Day weekend when she rode down in the elevator with Cedillo. About 10 minutes later, she got an alert that the hidden camera had been activated.

“He saw me leave, he saw me with my bag, and he knew I was heading out,” she concluded after viewing the video clip.

Chase, 26, called the cops, and Cedillo was busted for burglary as a sexually motivated felony and petit larceny.

Papers filed in Manhattan Supreme Court say he copped to the panty raid, admitting: “I went in today to look around. I took a pair of panties. I left, I went downstairs, I sniffed them, and I threw them in the garbage.”

The creep super added, “I went in another time a few months ago. I don’t remember when.”

Chase’s lawyer, Benedict Morelli, said, “We already got [Cedillo], and he’s going to jail,” but said Chase also plans to file suit Monday in Manhattan Supreme Court against Cedillo, landlords Vito and Michael Sacchetti and building manager TMS Management.

Neither the Sacchettis nor TMS Management returned phone messages.

Cedillo — who’s free on $50,000 bond — couldn’t be reached. His lawyer, Theodore Herlich, declined to comment.

Additional reporting by Rebecca Rosenberg, Dana Sauchelli and Bruce Golding