DENVER — The man accused of killing three people at a Planned Parenthood clinic in Colorado asked at least one person in a nearby shopping center for directions to the facility before opening fire, a law enforcement official said, offering the clearest suggestion yet that he was targeting the reproductive health organization.

The official was not authorized to publicly discuss the investigation and spoke to The Associated Press on condition of anonymity.

Prosecutors this week plan to charge Robert Lewis Dear, 57, with murder and other crimes in the Nov. 27 attack that also left nine other people wounded. Colorado Springs police have refused to discuss a motive for the fusillade, but there's mounting evidence to suggest Dear was deeply concerned about abortion, having rambled to authorities about "no more baby parts" after his arrest.

Dear asked at least one person in the nearby shopping center where the Planned Parenthood was earlier that morning, the official said.

Related: Victims of Planned Parenthood Shooting Identified as Mother of Two, Army Veteran

A second law enforcement official said Dear assembled propane tanks around a vehicle and brought at least 10 guns, including rifles and handguns, to the clinic, where he swapped gunfire with officers during an hours-long standoff. It was unclear whether Dear purchased all of them, but despite brushes with the law, he had no felony convictions that would have prevented him from buying a firearm.

Planned Parenthood cited witnesses as saying the gunman was motivated by his opposition to abortion.

Related: Who Is Robert Dear?

A Colorado Springs police spokeswoman on Monday referred questions about the investigation to El Paso County Sheriff's spokeswoman Teri Frank, who said she could not comment on the ongoing investigation.

Dear had been living in remote locations without electricity or water and was known to hold survivalist ideas. One of his three ex-wives, Barbara Mescher Micheau of Moncks Corner, South Carolina, said he had vandalized a South Carolina abortion clinic at least 20 years earlier, announcing to her that he had put glue in the locks of its doors, a common protest technique among activists trying to shut down abortion clinics.