SAN ANTONIO (Reuters) - Michael Horne‘s nightmare began when his grandmother‘s ashes tested positive for drugs. But knowing „Grandma wasn‘t a doper,“ Horne has filed a federal lawsuit against the city of San Antonio charging that a police mistake landed him in jail for a month and cost him his job, his truck and his apartment. The problems started on July 30, 1997 when Horne pulled off the side of the road to take a nap in his truck. A police officer stopped to question him and ended up searching the vehicle. In the truck‘s console, the officer found an envelope filled with a powdery substance that he suspected of being illegal drugs. He called in the narcotics unit, which chemically tested the powder on the scene and declared that it was methamphetamines, more commonly known as speed. Horne told police the powder was his grandmother‘s ashes, but they thought he was lying and put him in jail on drug charges, according to the suit. „It was Grandma, but nobody would believe the poor guy no matter how much he screamed and shouted,“ Horne‘s attorney Luis Vera said. Horne cooled his heels behind bars for a month before laboratory tests showed the ashes were human remains, not drugs. The case was dismissed and Horne freed. Horne, who had recently gotten out of the Army, was given the ashes by his grandfather so he would always remember his late, cremated grandmother and had not yet taken them from his truck. He said it was hard to believe the police mistook the ashes for drugs because speed „looks like baby powder“ while the ashes were various shades of gray, white and black. He thinks police may have lied about performing the initial tests and said the ashes were drugs because they believed them to be. But assistant city attorney Amy Eubanks said the officers had diligently carried out their duties. She said the crux of the problem may have been an unexplained delay in getting laboratory tests to confirm the field tests. The lawsuit charges that police violated Horne‘s constitutional rights and denied him due process of the law. Vera said it was also important to lay to rests any doubts about Horne‘s grandmother. „Grandma wasn‘t a doper,“ he said.