Iowa mom buys semiautomatic rifle for teen son -- and his friend is accidentally killed by it the next day

An Iowa mother was charged nearly a year after she bought her teenage son a rifle that accidentally killed his friend the very next day.

Police said 14-year-old Emma Redlinger was fatally shot in the head Feb. 28, 2015, while some teenagers handled a semiautomatic rifle at a friend's house in Vinton, reported The Gazette.

Federal prosecutors have charged 52-year-old Robyn Merchant with one count of providing a firearm to a prohibited person.

Investigators did not provide details about the events that led to the teen's death, but they said Merchant's son tested positive for marijuana and admitted to smoking marijuana regularly by age 15.

Merchant admitted she knew about her son's regular marijuana use when she gave him the Walther HK MPS 22LR semi-automatic the day before Emma was killed.

Police said they seized about 7 ounces of marijuana individually packaged from 16-year-old Dillon Winterroth's bedroom, along with a pipe and other drug paraphernalia, the newspaper reported.

Investigators determined the shooting was accidental, but two other adults and three teenagers were charged in her death.

Dillon Winterroth, now 17, was charged with felony counts of possession of marijuana with intent to deliver and failure to affix drug tax stamp. He was also charged with misdemeanor counts of making false reports to law enforcement, possession of drug paraphernalia, interference with officials acts and harassment of public officer or employee.

Police identified the teen who discharged the gun as 17-year-old William Hines, who was charged with misdemeanor counts of involuntary manslaughter and interference with official acts and harassment of a public officer or employee.

Prosecutors also charged 21-year-old Chase Merchant and 33-year-old Skylar Merchant with misdemeanor counts of possession of marijuana and possession of drug paraphernalia.

Only Robyn Merchant was charged in federal court.

Aimee Redlinder told The Gazette last year that her daughter had been an organ donor, and she said the Iowa Donor Network said her organs had been used to help six other people.

Watch this video report posted online by KCRG-TV: