A four-month undercover investigation at the Ogden Internal Revenue Service Center has resulted in the arrest of 10 people - eight of whom worked at the center - on charges of selling cocaine and marijuana.

John Dietz, IRS assistant regional inspector, said the IRS Internal Security Division conducted the investigation after several employees expressed concern about drugs at the center, which processes federal tax returns for several Western states.All defendants were expected to enter pleas Friday in U.S. District Court in Salt Lake City.

Charged with distributing cocaine or aiding and abetting its distribution are Louis Sandoval, an IRS clerk (two counts); Kenneth Hardison, a security guard (three counts); and cleaning crew members Todd Williams (five counts), Lori Thompson (three counts) and Michael Long (one count).

Charged with distributing marijuana or aiding and abetting its distribution are Thompson (one count); Long (one count); IRS clerks Alexander Cota (two counts) and Eligio Zuniga (three counts); and William C. Noker and Richard Conrad, who do not work at the center, charged with one count each.

Also, Ernesto Dominguez, an IRS maintenance worker, was charged with one count of aiding and abetting distribution of a controlled substance and one count for the intentional use of the telephone in distribution of a controlled substance.