Police believe man found in lake was killed

AUGUSTA - The body of a mentally disabled man was found floating in Lake Olmstead on Thursday, and authorities said they believed it to be a homicide case. <br> <br> Marty Thomas Gibson, 48, was seen by neighbors at 3 a.m. outside his home, drinking heavily. Five hours later, a fisherman found him a mile away near the Broad Street bridge. <br> <br> ``We&#39;re treating the case like a homicide because of evidence we found at the scene,&#39;&#39; Richmond County sheriff&#39;s Maj. Ken Autry said, declining to give specifics. <br> <br> Relatives said Gibson, who lived with his father and step-mother, was mentally disabled and suffered epileptic seizures. <br> <br> There were no visible signs of trauma, police said. Coroner Leroy Sims pronounced him dead at the lake, formed by a dam that expands the Augusta Canal. <br> <br> The body was sent to the state crime lab in Atlanta for an autopsy.