Missoula homeowner Markus Kaarma is charged with deliberate homicide in last month's slaying of 17-year-old Diren Dede of Hamburg, who authorities said was killed while "garage hopping" in a possible search for alcohol.
German officials have expressed outrage at the killing, and the teen's father suggested in an interview with a German news agency that US gun culture was at least partly to blame for his son's death.
Defence attorney Paul Ryan has said his client would invoke Montana's "Castle Doctrine" as a defence, which allows use of force to defend against a home invasion if the person inside reasonably believes it is necessary to prevent an assault.
State legislation places the burden of proof for "justifiable use of force" with prosecutors, Ryan said.
On the night of the shooting, Dede and a fellow exchange student from Ecuador were walking along the street when Dede approached Kaarma's garage, the Ecuadorean told police in an affidavit.
The Ecuadorean student assumed Dede was looking for alcohol and started to walk away, court papers said. He then heard an unfamiliar man's voice and four gunshots and began to run, the court papers said.
A former US Forest Service firefighter whose house had recently been burglarized, Kaarma was alerted to Dede's presence by motion sensors and a video monitor installed after the burglaries.
Prosecutors say he walked outside and fired a shotgun into his darkened garage, killing Dede, who according to court documents had been visiting Montana for a single school term and staying with a host family two houses away.
Kaarma, 29, could receive a prison sentence of between 10 and 100 years if convicted. He declined to answer questions outside court.
Kaarma remains free on $30,000 bail, after the judge in the case declined a prosecutor's request to raise his bail to $500,000. The prosecutor had called Kaarma a danger to the community.
The judge set the next hearing in the case for June 25.
