Investigators believe that Brandon Andrew Clark was enraged and killed Bianca Devins because she kissed someone else, according to the Oneida County District Attorney.

"We have reason to believe an incident occurred either at the concert they attended or before it where she kissed somebody else and he (Clark) was upset about that,'' District Attorney Scott McNamara told Syracuse.com | The Post-Standard today.

Clark, 21, of Cicero had been dating Devins, 17, of Utica for two to three months, police said.

The two attended a Nicole Dollanganger concert in Queens on Saturday night.

Police believe Clark became jealous when Devins kissed someone else. Police have said they were reviewing videos from the concert as part of their investigation.

Police have said the two argued at the concert before returning to Central New York early Sunday morning.

Police say Clark slit Devins’ throat, killing her Sunday morning in Utica. Then, in front of officers, he slit his throat and took a selfie. He survived and is currently hospitalized.

Clark was charged with second-degree murder on Monday night.

Clark posted photos of Devins’ bloody body on Instagram and on Discord, an online messaging app popular with videogamers. He changed his biography on Instagram to read July 14 (Sunday) as his date of death.

He took selfies just before and after stabbing himself in what police believe was a suicide attempt.

The gory photos were removed by Instagram, but remain online on various sites. The murder created a firestorm of online posts and commentary as well as international news coverage.

Utica police have said the two met each others’ families, and Devins’ family trusted him enough to let her attend a concert with him.

Clark has not answered questions, involving his right to counsel, police said.

Kimberly Devins, Bianca Devins’ mother, said her family is devastated by her daughter’s death.

“Our lives are now forever changed; our hearts are broken,” Kimberly Devins said in a statement released Wednesday. “My heart is completely shattered, having lost my best friend."

Nine years ago, Brandon Clark’s father, Jason, held Brandon’s mother hostage in a stand-off with Fulton police and an Oswego County SWAT team in Fulton, according to court records and the Syracuse.com | The Post-Standard archives.

Jason Clark held his wife hostage for 10 hours, holding her at knifepoint and threatening to slit her throat and kill himself, according to court records and past news articles.

Brandon Clark was about 12 years old at the time.