LENEXA, Kan. (AP) — The former owner and operator of a Kansas City-area lab is accused in a federal indictment of illegally storing radioactive material that tainted a building at an industrial park, costing U.S. taxpayers $760,000 to clean up.

The indictment returned Thursday alleges 61-year-old Ahmed el-Sherif’s Beta Chem Laboratory in Lenexa, Kansas, was licensed by Kansas to use radioactive Carbon-14 and solvents. But he eventually lost that permission after an inspection found extensive radioactive contamination in the lab.

After the state seized the lab, federal environmental investigators in 2014 found containers with hazardous wastes and tainted with radiation.

The indictment alleges el-Sherif submitted bogus tax returns as part of the government’s efforts to assess his ability to pay for cleanup costs.

Online court records don’t show whether el-Sheriff has an attorney.