16-year-old Tristan Stahley was arrested and charged with murder.
Authorities say Stahley and 17-year-old Julianne Siller were overheard arguing at his home on Rittenhouse Lane.
A short time later, the couple drove to nearby Palmer Park and the argument continued as they walked along the trail.
Police say Stahley attacked Siller, stabbing her multiple times including in the throat.
After the attack, he allegedly dragged Siller's body to a densely wooded area.
Stahley fled the scene, went home and told his mother.
Stahley then threatened to commit suicide. Police were called as the teen's father stopped him from trying to harm himself.
Authorities took Stahley into custody where they say he admitted stabbing Siller with an EMT knife and dragging her body into the woods.
Investigators were able to recover Siller's body later that night.
On Sunday night, Siller's friends brought stuffed animals and flowers to remember her.
Some even took to social media. Katie Roach tweeted to Action News, "She's beautiful. One of the sweetest girls you'll ever meet. She has a one of a kind personality and laugh. She has a carefree soul."
According to court documents, Siller and Stahley have been dating since January.
Stahley was arraigned Sunday and remains in custody without bail.