Image copyright AP Image caption Defence lawyers said Kaarma shot in self-defence under the state's "castle doctrine" law

A Montana man has been sentenced to 70 years in prison for killing a German exchange student last year.

Markus Kaarma fatally shot Diren Dede, 17, of Hamburg last year after the teenager entered his garage.

He was convicted of deliberate homicide in December. Defence lawyers said Kaarma had shot in self-defence.

Diren, a football player, was attending Big Sky High School in Missoula, Montana, for one year as part of an exchange programme.

Kaarma's lawyers plan to appeal the conviction and sentence. He will not be eligible for parole for 20 years.

The son of a family of Turkish immigrants to Germany, Diren had only six weeks left in the exchange programme.

Image copyright AP Image caption Dede's parents embrace after Kaarma was found guilty

"It is justice. I am not happy. My son is dead." his father, Celal Dede, said after the sentencing.

Mr Kaarma, a 29-year-old firefighter, has told investigators his home had twice been hit by burglars, and he told a hair stylist he had waited up at night to shoot intruders, prosecutors said.

On the night of the shooting, Mr Kaarma and his partner Janelle Pflager left their garage door open, and Ms Pflager left her purse in the garage in order to bait intruders, she told police.

They set up motion sensors and a video monitor, prosecutors said.

When the sensors went off just after midnight and they saw a man on the monitor screen, Mr Kaarma went outside and fired a shotgun into the garage without warning several times.

It is unclear what the teenager was doing inside in the garage.

The case also brought scrutiny to Montana's so-called "castle doctrine" law, which allows homeowners to use deadly force if they "reasonably believe" an intruder is trying to harm him or her.