Haunting photos show Long Island teen Emily Finn happily dancing at prom with her ex-boyfriend who allegedly killed her in a botched murder-suicide before Thanksgiving.

Austin Lynch, 18, who awaits arraignment Friday in Suffolk County court, can be seen posing with and hoisting Finn, 18, in social media pics from the dance – months before their fateful breakup and the senseless shooting.

Other photos of Lynch unearthed by The Post chillingly show him pose with a gun.

Long Island teen Emily Finn is seen in haunting photos happily dancing at prom with Austin Lynch, who allegedly killed her in a botched murder-suicide. emily_finn1015/Instagram

The pics were taken months before their breakup. emily_finn1015/Instagram

Lynch allegedly gunned down Finn inside his Nesconset home Wednesday as she returned some of his belongings after their recent split, police have said.

He then shot himself in the face, but survived and likely will face a second-degree murder charge, cops said.

A family friend of Lynch said the teen was heartbroken about his “puppy love” romance with Finn coming to an end.

Lynch could be seen with a gun in some photos. Jason Lynch.Facebook

“People are in the comments like, ‘she must’ve done something to him,’ No, she didn’t,” the friend said.

A trail of social media photos provides a glimpse into their doomed relationship, including a apparent pre-prom pic showing Finn beaming, bedecked in a magenta dress, alongside a tightlipped Lynch clad in black.

The pair were apparently close enough that they went on a vacation in Aruba together.

Lynch’s mother’s Facebook cover photo is a group shot of her family — and Finn — posing on a beach.

Lynch allegedly killed Finn on Wednesday inside his Nesconset home. Facebook/Melissa Lynch

The alleged killer teen, who is recovering from his self-inflicted gunshot wound, will be arraigned when doctors and a judge deem him medically alert, Suffolk County district attorney officials said.

— Additional reporting by Desheania Andrews and Peter Senzamici