Mark Edward Calder, 36, of Bountiful, is accused in a federal complaint of one count each of possession of child pornography and transportation of child pornography. He has been jailed pending a hearing today in U.S. District Court in Salt Lake City.

Now investigators are asking the public for information about any contact Calder, who drives a 2001 Audi TT with a Utah license plate that says "MARQUE," had with minors.

The suspect was arrested Friday outside a West Valley City arcade. Investigators had spotted him earlier in the day shopping with twin girls, who are about 8, in the children's sections of two Kmarts. Calder told police the girls were friends of the family, according to court records.

In addition to the child pornography charges, Calder is being investigated for possible identity fraud, the U.S. Attorney Office in Utah says. The child pornography transportation charge carries a maximum penalty of 30 years in prison, and the maximum for possession is 10 years.

A statement by agent Adam Parks of Immigration and Customs Enforcement (ICE), filed with the federal complaint, says Calder tried to enter Canada by car at the Cascade, British Columbia, port of entry July 29. A Canadian customs officer who questioned him became suspicious, and Calder's vehicle and laptop computer were searched.

Text files describing children ages 9 to 14 involved in incest, rape and sex with adults were found, according to Parks' statement. The agent says officers also discovered five pairs of girls' soiled underwear and three sex toys in the car trunk, as well as a printout of a Canadian hotel reservation for two adults and two children, ages 7 and 10.

Canada informed U.S. authorities that it was investigating Calder and, in turn, ICE and the Utah Identity Theft Task Force launched their own probe, leading to Friday's arrest.

The ICE statement says Calder admitted he had mailed a laptop and three compact flash cards containing child pornography to his Bountiful home and had possessed movies of minors engaging in sexual conduct. He also allegedly admitted stealing youngsters' underwear and maintaining a fictitious identity under the name Marque Cawder.

Anyone who has information about suspicious activity by Calder or who is aware of unsupervised contact he had with children is asked to call the FBI at 579-1400. An agent will return calls.

pmanson@sltrib.com