A Quakertown man suspected of building and detonating a series of bombs in Bucks County in the spring now faces child-pornography charges.

David Surman Jr., 30, was arraigned Wednesday after surrendering to police. He was freed after posting 10 percent of his $500,000 bail and is due back in court for a preliminary hearing Oct. 23.

He had been out on bail since his arrest in the bombing case, after his mother, Kathy L. Surman, posted 10 percent of $750,000, court filings show.

Surman gained widespread attention in June, when a combined task force of local, state, and federal investigators raided his home and the chemical company he owns nearby as they investigated a series of mysterious, late-night explosions in rural townships in upper Bucks County. Warrants unsealed last month show that investigators were led to Surman after a state trooper spotted him speeding away from the site of one of those blasts.

State police investigating the bombing case had executed a search warrant in July for various electronic devices seized in Surman's home, including thumb drives, cell phones, digital cameras, and laptop computers, according to court documents. During a search of those devices last week, a state trooper discovered a picture he identified as child pornography.

The trooper submitted a second, more expansive warrant for Surman's devices, and it was executed Sunday. During that search, investigators found a collection of pornographic images and videos depicting children, according to an affidavit of probable cause filed Wednesday.

As state police built the child-pornography case against him last week, Surman waived his right to a preliminary hearing on the criminal charges he faces in connection with the bombings: possessing a weapon of mass destruction, reckless endangerment, and related offenses. He faces an arraignment in county court next month, ahead of a criminal trial tentatively scheduled to begin in February.

After the car stop that first brought Surman to their attention, investigators probing the bombings delved deeper into his background.

They noted that Surman's company, Consolidated Chemicals & Solvents, sold many of the same chemical compounds detected in soil samples taken from various explosion sites around the county. One of his clients was also under investigation by the FBI in Houston for an unrelated matter, according to a search warrant filed in the case.

When police went to arrest Surman, they found a large, 18-inch explosive in his home, one that District Attorney Matt Weintraub described at the time as being capable of causing "mass destruction." Surman's motive for the alleged bombings remains unclear.

Police believe the devices used to cause the explosions were "being deployed from the right (passenger) side of a vehicle," according to court paperwork.

An SUV matching the description of the one Surman was riding in the night he was stopped was seen on surveillance footage fleeing the scene of other explosion sites. That vehicle, a Ford Explorer, is owned by Surman's girlfriend, Tina Smith. She does not face criminal charges in the case, and prosecutors say she has been cooperating with the investigation.