A 15-year-old Fond du Lac resident is in custody following an investigation into a threatened mass shooting.Police said they received a tip last month into online statements allegedly made by the teen about a potential mass shoo ting.On Oct. 27, detectives executed a search warrant at the teen's home, where they seized multiple firearms, a computer and a cellphone, police said. Investigators are now conducting forensic examinations of the devices to verify the information they received and better understand the context of the juvenile's online activity.Police said detectives interviewed the teen again Tuesday. Following that interview, the juvenile was evaluated by Fond du Lac County Human Services Youth Justice social workers and placed in the Fond du Lac County Secure Detention Facility.Investigators have referred one count of making terrorist threats and one count of disorderly conduct to Fond du Lac County Human Services Youth Justice. The investigation remains ongoing.Because the case involves a juvenile, police said no additional identifying information will be released. Anyone with information about potential threats or concerning behavior is encouraged to contact law enforcement. ...read more read less