By Laura Zuckerman
May 6 (Reuters) - A Montana homeowner may have been high on marijuana or alcohol when he shot dead a German exchange student in his garage in a case expected to test the state's "stand your ground" self-defense law, prosecutors said in legal documents released on Tuesday.
Markus Kaarma, a 29-year-old U.S. Forest Service firefighter, fired his shotgun into his darkened garage in Missoula, Montana after midnight on April 27, killing 17-year-old Diren Dede, a high school student from Hamburg, Germany, police have said.
Kaarma "may have been impaired by alcohol, dangerous drugs, other drugs, intoxicating substances or a combination of the above at the time of the incident," a Missoula police detective said in a sworn statement.
Kaarma will plead not guilty at an upcoming arraignment, his lawyer Paul Ryan said.
Kaarma will invoke the state's so-called castle doctrine, which among other things allows the use of force to defend against an invasion of a home or structure if the person inside reasonably believes it is necessary to prevent an assault.
A national debate on the use of force and "stand your ground" laws has raged since the shooting death of unarmed Florida teenager Trayvon Martin by George Zimmerman, who was acquitted of murder in July last year.
A search warrant obtained last month by Missoula police seeking a vial of Kaarma's blood for testing shows authorities suspected Kaarma was high on marijuana or alcohol when he shot and killed Dede.
An earlier authorized search of Kaarma's home revealed a glass jar containing pot. A neighbor told police that Kaarma's wife said he smoked pot in the garage and that marijuana and pipes used to smoke it had been stolen there during a previous burglary, according to legal documents filed by prosecutors.
Kaarma's attorney Ryan declined on Tuesday to comment on those allegations. Ryan said an exchange student from Ecuador who was at the Kaarma home during the shooting told police that he and Dede were behind a rash of Missoula garage burglaries.
Kaarma feared for his life and for the safety of his wife and their 10-month-old son when a male intruder later identified as Dede entered the attached garage, and advanced toward the couple's kitchen, Ryan said, adding a security camera taped the intruder.
(Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Eric M. Johnson and Michael Perry)