The college student accused of a five-state mailbox pipe bomb spree asked that his preliminary court hearing be waived.

Defense attorney Jane Kelly filed papers Wednesday in U.S. District Court in which Luke Helder, 21, of Pine Island, Minn., acknowledged he was entitled to a preliminary hearing, but asked that it be waived.

The hearing, which had been set for May 22, would determine whether there is probable cause to believe Helder had committed a crime.

Helder is accused of placing pipe bombs in 18 mailboxes, six of which detonated, injuring four letter carriers and two Iowa women between May 3-6.

He faces identical charges of using a pipe bomb in a crime of violence and destroying property used in interstate commerce in federal court in Des Moines. He also has been charged in Illinois and Nebraska.

Helder, who faces life in prison if convicted, was being held without bail in the Linn County Jail.

A woman answering the phone at the federal public defender's office said Friday that Kelly would not return media calls.