Police in Lansing, Michigan, are investigating whether a possible serial killer is responsible for five deaths along the city’s River Trail over the past year.

The victims were homeless men ranging in age from 22 to 70, and investigators believe several may have been attacked while sleeping outdoors during the early morning hours.

Three deaths have been classified as homicides, while the circumstances surrounding the other two remain unclear.

Authorities have arrested a suspect in the fatal stabbing of 22-year-old Daniel Lusk, but he has not been linked to the other deaths, NBC News has reported.

Police have increased patrols, installed camera trailers along the trail and urged the public to provide information as investigators work to determine whether the cases are connected.