AMHERST, Wis. (AP) – Three Portage County residents are accused of cashing the Social Security checks of a relative who’s been missing for 30 years.  If Marie Jost were still alive she’d be 100 years old. But authorities now suspect she died about 30 years ago, and they accuse her son, daughter and son-in-law of continuing to cash her government checks.  Investigators say Jost might be buried on her Amherst property. Sheriff’s Capt. Dale O’Kray says authorities are using heavy machinery to explore the property and see whether they can find her remains.  Charges including theft and mail fraud have been filed against 66-year-old Charles T. Jost, 69-year-old Delores M. Disher and 71-year-old Ronald Disher.  The attorney for Ronald Disher declined comment Tuesday. Messages left with the other two defense attorneys weren’t immediately returned.