NORRISTOWN — A Skippack teenager accused of fatally stabbing his girlfriend will head to trial in September and through his lawyer hinted in court he is exploring a potential “diminished capacity” defense.
Tristan Brian Stahley, who recently turned 18, appeared in Montgomery County Court on Thursday for a case status hearing before Judge William R. Carpenter, who scheduled Stahley’s jury trial to commence Sept. 29 in connection with the alleged May 25, 2013, stabbing death of 17-year-old Julianne Siller, of Royersford.
Testimony revealed that attempts by Stahley’s lawyer to hire a “diminished capacity” expert in preparation for trial have led to recent delays in setting a trial date. But defense lawyer Timothy J. Barton indicated to the judge on Thursday that a trial date could now be set.
However, Barton didn’t reveal if he’s obtained an expert’s report or if he will actually move forward with a diminished capacity defense on behalf of Stahley.
Wearing a red jailhouse jumpsuit, Stahley, who was 16 at the time of the alleged murder, declined to comment about his case as he left the courtroom, escorted by sheriff’s deputies, for the return trip to the county jail where he is being held without bail while awaiting trial.
“We remain prepared for trial,” Assistant District Attorney Jeremy Abidiwan-Lupo said after the hearing, which was attended by two of Siller’s relatives.
Stahley, of the 4100 block of Rittenhouse Lane, faces charges of first- and third-degree murder and possession of an instrument of crime in connection with the fatal stabbing of Siller, who was a senior at Spring-Ford Area High School. Because of the violent nature of the crime, Stahley was charged as an adult.
With a diminished capacity defense those accused of murder typically attempt to reduce first-degree murder, which is an intentional killing, to a lesser charge by contending they didn’t have the mental state to intentionally cause a death.
Under state law, while first-degree murder requires a specific intent to kill, third-degree murder is a killing that occurs with malice or recklessness.
If he’s convicted of first-degree murder, Stahley could face a sentence of life imprisonment. A conviction of third-degree murder carries a possible maximum sentence of 20 to 40 years in prison.
Stahley, a former Perkiomen Valley High School student, and Siller had been dating “off and on” for about six to nine months at the time of the incident, according to court papers. The couple drove to the park off Creamery Road where they argued about Siller smashing Stahley’s phone and going out without him, according to court documents.
“Tristan said he used an orange handled EMT knife and stabbed Julianne in the throat and on her body,” according to the criminal complaint filed by county Detective Paul Bradbury and state police Trooper Barry Bertolet. “After the stabbing, Tristan said he then drug Julianne’s body into the woods to conceal her body.”
Authorities alleged the paramedic-style knife was found about 10 feet from Siller’s body.
After the alleged killing, Stahley returned home and threatened to kill himself with another knife shortly after confessing to his mother. Stahley’s father attempted to stop his son from committing suicide and struggled with the teen, suffering scratches to his face and a bite to his hand in the process, according to the arrest affidavit.
State police responded to the Stahley home about 10:21 p.m. for a report of a domestic disturbance and diffused the struggle between father and son. At that time, Stahley allegedly confessed to police and led troopers to Siller’s body.
An autopsy determined Siller died from multiple stab and cutting wounds.
Follow Carl Hessler Jr. on Twitter @MontcoCourtNews