German authorities may charge the father of the teenager who killed 15 people in a shooting rampage March 11 with involuntary manslaughter.

Tim Kretschmer, 17, went on a rampage Wednesday at Albertville technical high school in Winnenden, northeast of Stuttgart, killing nine students and three teachers.

He then shot and killed three more people at another location before killing himself.

Police spokesman Klaus Hinderer said prosecutors in Stuttgart are considering charging the father because the 9-mm Beretta pistol used in the shootings belonged to him.

His name has not been released.

The gun, one of 15 he owned, was kept unsecured in his bedroom in violation of German law.