Celebrity news outlet TMZ reported Wednesday that it was approached by someone attempting to sell the photos, which show Dorner's scorched and partially dismembered body.
Sheriff's spokeswoman Jodi Miller said the department is looking into the matter.
"We do not believe those are Sheriff's Department photos," Miller said. "We believe they were possibly obtained after Christopher Dorner's body was released to a private mortuary and that occurred on Feb. 16."
Sheriff's Capt. Kevin Lacy, who oversees operations at the San Bernardino County Coroner's Office, said an investigation determined Dorner's body was secured until the time the department released his body to the mortuary shortly after midnight Saturday.
"We have procedures in place to make sure bodies are secure in our custody," Lacy said.
"After hearing this story that somebody was shopping photos to TMZ, we audited our records pertaining to Mr. Dorner's transport, and I can tell you those photos were not taken by coroner personnel."
Lacy would not disclose the name of the mortuary to which Dorner's remains were released.
"Once we release it and the mortuary takes possession, at that point, it really becomes a point of the next of kin to decide whether they want to disclose that," Lacy said.
TMZ officials said they did not purchase the photos, which show that Dorner's body was missing limbs as well as the top of his head.
However, his upper teeth were barely damaged, which presumably aided Riverside County coroner's officials in identifying the body.
Riverside County sheriff's spokeswoman Sgt. Lisa McConnell said she had not heard about the photos and referred all comments to the San Bernardino County Sheriff's Department, which served as the lead agency in the investigation.
Sheriff's officials contend Dorner's death on Feb. 12 was the result of a self-inflicted gunshot to the head.
Dorner, a former Los Angeles police officer, was the subject of a massive manhunt after allegedly killing two people on Feb. 3 in Irvine and a Riverside police officer on Feb. 7.
Dorner's body was discovered inside a cabin in Barton Flats following a shootout with law enforcement. Dorner is suspected in the killing of a San Bernardino County sheriff's detective in the gun battle.
To get Dorner out of the cabin, law enforcement fired tear gas into the cabin, which caught fire, burning it to the ground with Dorner still inside.