Kansas City, Mo. ? A Kansas chemist is accused in a federal indictment of illegally storing radioactive material that contaminated his now-closed lab in a suburban Kansas City industrial park, costing U.S. taxpayers $760,000 to clean up as a Superfund site.

Thursday’s indictment and federal prosecutors did not specify Ahmed el-Sherif’s source of isotope Carbon-14 and Radium-226 that he used to process pharmaceutical compounds at his Beta Chem Laboratory in Lenexa.

Radioactive materials commonly are used in research to create and test new medicines, according to the U.S. Environmental Protection Agency’s website, which also notes research labs must follow strict rules when ordering, storing, using and disposing of radioactive material.

Radium that is swallowed or inhaled can accumulate in a person’s bones. Long-term exposure increases the risk of developing several diseases, such as lymphoma, bone cancer and diseases that affect the formation of blood, the EPA says.

Online court records Friday did not list an attorney for el-Sherif, the lab’s “radiation safety officer” accused of illegally storing hazardous waste and obstruction by providing bogus Beta Chem tax returns meant to demonstrate his ability to cover the site’s cleanup costs.

El-Sherif is a prominent regional Muslim and interfaith leader, having founded the American Muslim Council of Greater Kansas City.

The indictment alleges el-Sherif was licensed by Kansas to use Carbon-14 and solvents but eventually lost that permission after an inspection found extensive radioactive contamination in the lab.

After the state seized the lab in October 2013, EPA investigators a few months later found numerous containers containing hazardous wastes and tainted with radiation. Of 1,134 at the lab screened, most contained hazardous waste and “almost all of the containers had elevated levels of radiation,” according to the indictment.

The indictment did not say if people other than el-Sherif had access to the tainted lab.

The EPA completed the cleanup in March 2015.