By Shereen Siewert UPDATE 12:38 p.m. A “suspicious person” in Mosinee that prompted a lockdown at area schools is in custody and operations are back to normal Tuesday, according to an email from school officials. All Mosinee schools instituted a secure perimeter for about an hour Thursday following a report of a suspicious person in the city, according to an email sent to parents. Mosinee School Superintendent David Munoz sent the letter just after 11:15 a.m. Thursday alerting parents to the situation. A secured perimeter means no one enters or exits the building without explicit administrative approval. All students and staff are safe. No additional information regarding the suspect or what prompted the lockdown was immediately released.