A Utah man arrested Saturday at Logan International Airport was held on high bail following his arraignment for allegedly possessing child pornography, Suffolk County District Attorney Daniel F. Conley said today.

Assistant District Attorney Erik Bennett of Conley’s East Boston District Court staff recommended that GRANT D. SMITH (D.O.B. 5/28/64) of Cottonwood Heights, Utah, be held on $150,000 cash bail; Judge Kenneth V. Desmond imposed bail of $75,000.

At Bennett’s request, Desmond imposed a series of conditions that Smith must abide if he posts bail: He must have no unsupervised contact with any child under 16; he must not use the internet except as required professionally; and he must allow the Department of Probation or any law enforcement official acting on Probation’s behalf to search his personal and work computers and digital media at any time.

While Smith’s Delta flight from Utah was in the air en route to Boston, Massachusetts State Police assigned to the Logan Barracks were notified that Smith was viewing what appeared to be child pornography on his laptop computer. Specifically, a fellow passenger who observed Smith’s computer screen notified the flight crew and a family member, who in turn notified law enforcement. That fellow passenger, a Scottsdale, Arizona, man, is not being identified.

State troopers met Smith’s flight at about 4:30 Saturday afternoon and interviewed him upon his arrival. During that interview, Smith granted written consent for a trooper assigned to the Internet Crimes Against Children Task Force to view his MacBook Pro, which he said was purchased through a research grant from his employer, the University of Utah. Smith allegedly said he was its sole user.

Troopers recovered from that computer multiple still images depicting young girls, some naked and some engaged in explicit sexual activity with adult males. Based on captions embedded in the images and troopers’ estimates, the children depicted were between the ages of 5 and 14 years old.

“These weren’t photos of a child in the bath that a parent might keep,” Conley said. “These were explicitly sexual and extremely disturbing.”

Smith’s laptop and iPhone were seized as evidence. Investigators will seek a search warrant to conduct a thorough forensic examination of their contants.

Under Massachusetts law, even possessing child pornography is punishable by up to five years in state prison. A person convicted of that offense must also register as a sex offender.

Smith was represented by attorney Patrick Murphy. He will return to court on Dec. 27.