Suspicious behavior by a customer at a mailing business led to a Billings man's admission that he distributed LSD from a source in the Netherlands.

The customer, Robert Hauge, 28, pleaded guilty last week to a federal charge of possessing at least 10 grams of LSD, a hallucinogen, for distribution. A second count of trafficking Ecstasy, a stimulant, is to be dismissed at sentencing under the terms of a plea agreement. Hauge's case had been set for trial Monday.

An investigation by federal and local officers began in October 2007 after employees of PostNet, 2912 Grand Ave., reported that Hauge had visited the store almost daily in the previous two months to use the store's public computer and to mail packages to the Netherlands and other locations in the United States, court records said. Hauge minimized the screen and put his face close when he used the computer.

When Hauge left the store, the employees checked the computer's Internet history and saw Web sites related to LSD, Ecstasy, pill reports and the making of identification cards.

A month later, Hauge brought in four packages to be mailed. Investigators had a sniffing dog check eight packages, and the dog responded to Hauge's four packages. Armed with a search warrant, officers opened the packages and found $6,400 in a package to be sent to Amsterdam and LSD and Ecstasy tables in the three other packages.

Law enforcement officers obtained a search warrant for Hauge's home and found 2,300 doses of LSD and 1,600 Ecstasy tablets. Hauge told officers that he had been receiving the drugs from a source in Amsterdam for about a year.

The source would send Hauge the drugs, and he would distribute them to other customers. Hauge would mail cash back.

Hauge estimated he sent about $3,000 a month to the source and had received about 10,000 Ecstasy pills and 2,000 to 3,000 doses of LSD.

Hauge faces a minimum mandatory 10 years to life in prison and a maximum $4 million fine.

Chief U.S. District Judge Richard Cebull set sentencing for Sept. 30. Hauge remains in custody.