A contractor admitted that he failed to properly remove asbestos from an elementary school and pleaded guilty on Monday to a criminal violation of the Clean Air Act.

Branko Lazic, who owns Bilaz Inc., was hired to remove asbestos from Mattison Elementary School in Ambler, Pa., in June 2002, the Justice Department said.

Lazic left the school while the work was being done, although he knew his workers were unlikely to do the work properly, Justice Lawyers said in a statement.

Janitors and teachers were left to remove a white dust residue from floors and furniture before the next school year started, they said.

Lazic faces up to five years in prison, restitution and a $250,000 fine. His sentencing date was not immediately set.