The Irvine couple who were the first alleged victims of Christopher Dorner were likely stalked before being shot multiple times with a 9-millimeter pistol equipped with a high-capacity magazine, according to an affidavit for a search warrant.

Monica Quan, 28 and Keith Lawrence, 27, were found dead on the top floor of their condominium’s parking garage in Irvine on Feb. 3, days before the massive manhunt for Dorner took shape.

The killing of the Cal State Fullerton basketball coach and her fiance is believed to have been fueled by a quest for revenge for Dorner’s 2007 firing from the Los Angeles Police Department. Quan’s father -- a former LAPD captain -- represented Dorner at a disciplinary hearing that led to the termination.

PHOTOS: Manhunt for ex-LAPD officer

The Dorner manhunt came to a dramatic end Tuesday when the Big Bear-area cabin where he was holed up burned to the ground. His remains were positively identified Thursday. Authorities said that the former lawman's crime spree left four people dead, including two police officers, and three injured.

Irvine Officer Jonathan Sampson noted in the affidavit filed in Orange County Superior Court that Dorner “conducted background” on his targets and may be in possession of “journals, maps, photographs and documents containing personal and professional information for Keith Lawrence and the entire Quan family.”

Additionally, the document noted, a beanie and several shell casings were found near Lawrence’s white Kia.

TIMELINE: Manhunt for ex-LAPD officer

Two days after Lawrence and Quan were gunned down, police in National City discovered in a trash bin  leather duty gear, uniforms with name tags for Dorner and a high-capacity magazine for 9-millimeter bullets that were believed to belonged to Dorner, according to the affidavit.

Irvine police detectives also viewed surveillance video that showed Dorner discarding the items in the trash bin. The detectives then contacted the LAPD to discuss Dorner.

“We also learned that Dorner appeared to harbor a grudge about losing his job as a police officer,” Sampson wrote in the affidavit.

INTERACTIVE MAP: Searching for suspected shooter

Detectives also interviewed a friend of Dorner’s who was mentioned in a manifesto authorities allege he posted on Facebook. Portion of the manifesto are included in the affidavit.

The friend said that he and Dorner shared a common interest in firearms, according to the document. The two occasionally went to the desert and Dorner brought many “high powered rifles and tactical firearm accessories,”the detective wrote.

The affidavit said that Dorner also emailed his friend photos of “various firearms, weapon sights, suppressors [silencers], and high capacity magazines.”

WHO THEY WERE: Victims in the Dorner case

Dorner was planning to sell the weapons via the backpage.com website, according to the affidavit.

Police said they also searched Dorner’s Facebook page, bank accounts and backpage.com account.

In the warrant, Sampson wrote that Dorner could "pose a continuing threat to the public if not apprehended as soon as possible."

The warrant allowed police to search all of Dorner's bank records and online profiles. Police also received permission to search Dorner's family house in La Palma.

 This story was reported by Times Staff Writer Nicole Santa Cruz.