A county sheriff in Ohio says the subject of a nationwide manhunt has confessed to killing an elderly couple found dead inside their torched car.

Twenty-nine-year-old Robert Clark was arrested Thursday in Arizona after a high-speed chase. He has been charged with murder in the slayings of 88-year-old Doyle Chumney and his 79-year-old wife, Lillian.

Tuscarawas (tus-kuh-RAW'-uhs) County Sheriff Walt Wilson said Friday at a news conference that Clark has confessed to killing them. Clark remains jailed in Arizona.

Clark and two companions had been sought in a string of robberies last weekend in three states. The companions aren't suspects in the slayings.

Authorities say another man implicated himself and Clark in the killings. Twenty-one-year-old Jeffery Stewart was arrested last month and is being held on a $2 million bond.