MADISON, Wis. — One of two Wisconsin girls who tried to kill a classmate to win favor with a fictional horror character named Slender Man was sentenced Thursday to 25 years in a mental hospital, the maximum possible.

Anissa Weier, 16, pleaded guilty in August to being a party to attempted second-degree intentional homicide, but she claimed she wasn’t responsible for her actions because she was mentally ill. In September, a jury agreed.

Waukesha County Circuit Judge Michael Bohren on Thursday sentenced Weier to 25 years in a psychiatric institution, retroactive to the date of the crime.

Weier and Morgan Geyser lured Payton Leutner into a wooded park in Waukesha, a Milwaukee suburb, in 2014. Geyser stabbed Leutner 19 times while Weier urged her on, according to investigators.

Leutner survived after she crawled out of the woods to a path where a passing bicyclist found her.

Weier apologized in brief comments before her sentencing.

In a deal with prosecutors, Geyser pleaded guilty to attempted first-degree intentional homicide with the agreement that she isn’t criminally responsible and shouldn’t go to prison.

She will be sentenced in February, and prosecutors have asked that she be given at least 40 years in a mental hospital.

ASSOCIATED PRESS