LYONS (WWJ/AP) – Authorities have determined that human remains found in a mid-Michigan family’s yard in 1981 are Native American in origin and may be 1,000 or more years old.

A homeowner found the buried bones during a construction project in the Ionia County village of Lyons. State police recovered the remains and they ended up at Michigan State University.

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Detective Sgt. Michael Morey says an anthropologist determined the bones were from at least three adults.

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The bones and another set sent to MSU from Ithaca in 1971 became part of the school’s teaching collection, but now police are working to return them to tribes.

Morey picked the bones up from the East Lansing school on Wednesday. State police now have two years from the date he took possession of the remains to go through all the steps required by federal law, the Sentinel-Standard of Ionia reported.

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