The former Bend couple severely burned when their alleged clandestine home drug lab exploded in March was arrested this week on federal charges at their new home in Boring.

The full scale of the butane honey oil operation inside the home of David Carl and Jennifer “Jenn” Rose Paulsen, both 32, wasn’t known until weeks into the investigation, Bend Police Chief Jim Porter said Wednesday.

The Paulsens were arrested Tuesday by U.S. Marshals serving a warrant by the U.S. Drug Enforcement Agency. At 5:31 p.m. March 18, neighbors of the Paulsens rented duplex called 911 to report an explosion. Witnesses told police that in the moments after the blast, David Paulsen attempted to hide evidence in his Toyota Tacoma truck and attempted to convince a neighbor to lie and tell police the couple’s 3-year-old daughter had been with the neighbor “the whole time.”

The girl was uninjured in the blast, which was strong enough to lift the roof off the duplex structure and move the foundation by about half a foot, according to Bend Police.

Porter said the Central Oregon Drug Enforcement team took cues from U.S. Attorney for Oregon Billy J. Williams, who has prioritized combating the diversion of legally grown marijuana out-of-state and the use of legal marijuana for illicit uses.

Federal prosecutors deal with a higher burden of proof than those of the state, Porter said.

“Seldom do the federal agencies make a probable cause arrest on the scene,” he said. “What they prefer to do is, present their information to a grand jury, get indictments for the individuals and then go forward.”

Another factor delaying the investigation has been the severity of the Paulsens’ injuries, Porter said.

The Paulsens were taken to the hospital on the night of the blast with multiple, serious burns. They were interviewed by Bend officer Caitlin Doshier, who reported the couple individually told her a similar story claiming the only butane in their house was a minimal amount used to refill lighters and “clean scissors.”

“David said he believed the explosion was caused by a gas can that was in the garage near the furnace,” Doshier said.

The couple was initially arrested by Bend Police and only charged with the unlawful manufacture of a marijuana item and unlawful delivery of marijuana.

Back at the duplex at around 7 p.m., Oregon State Police Sgt. Dan Conner accompanied a Bend Fire Department investigator on a tour of the home. They noticed the strong smell of marijuana and a butane cannister. Melted and partially burnt items further pointed toward a butane explosion from a honey oil lab, Bend Police Detective Nick Lee wrote.

Investigators believed that the butane (which is heavier than air) had collected in the couple’s garage, which was situated a foot lower than the duplex’s main level. The likely ignition source was thought to be the gas furnace in the garage, which had an electric igniter.

Porter told The Bulletin the investigation grew in the weeks after the explosion as the scope of the Paulsen’s operation became better understood. Investigators looked into possible supply lines and the ultimate destinations of the product, as well as the money.

“It’s not something someone grows in their closet,” Porter said of butane honey oil. “It takes a large amount of marijuana to go through the extract process.”

It was determined the 134 pounds of marijuana used in the illicit operation had been grown legally. But the product had been diverted to the black market after state officials ordered it destroyed because it contained unhealthy pesticides.

The Paulsens now face the federal crimes of manufacturing or possessing with intent to manufacture, distribute or dispense hashish as well as endangering a human life while illegally manufacturing a controlled substance. Additional charges could come.

The CODE team works out of an office space inside Bend city limits. Porter said its location is confidential. The team is made up of representatives of various state and local law enforcement agencies. It also contains a federal contingent: two DEA agents and Steve Gunnels, a prosecutor for the local district attorney’s office who’s cross-designated as a federal prosecutor. That contingent helped build the federal case against the Paulsens.

Representatives of the DEA and the U.S. Attorney’s Office in Eugene did not respond to requests for comment.

— Reporter: 541-383-0325, gandrews@bendbulletin.com