The defense attorney for Christopher Watts, the Colorado man accused of killing his pregnant wife and two young daughters, filed a motion Friday requesting that DNA samples be taken from the recovered bodies of Shanann Watts, and daughters Bella and Celeste Watts.

But a Weld County District judge dismissed the motion, citing concerns about the credibility of the forensic expert consulted by the attorney, the Denver Post reported.

Authorties haven't yet revealed why they believe Christopher Watts is a suspect in the deaths of his family, but a sealed affidavit is expected to be made public Monday, the newspaper reported.

Media reports Friday said the bodies of the two girls were found this week submerged in oil and gas tanks on the property of their father's former employer, while the mother's body was reportedly found in "close proximity."

The defense motion filed Friday by defense attorney James Merson suggests that the girls were strangled, the Post reported. The court document cited Richard Eikelenboom, a forensic expert, who said any evidence of strangulation should be present on the necks of the girls, “in spite of the fact that the remains were in oil for four days.”

Eikelenboom further recommended obtaining DNA samples from Shanann Watts’ hands and nails.

“After samples are taken the nails should be cut preserved,” Eikelenboom was quoted in the document. “I have a lot experience taking samples from dead bodies getting good results after strangulation. The hands of the children should be sample as well.”

But according to the Post, Eikelenboom admitted during a 2016 sexual assault trial that he had no experience with DNA extraction or analysis and a Denver District Court judge subsequently barred Eikelenboom from testifying as an expert witness.

The coroner’s office announced Friday it is has positively identified the victims as Shanann, Bella, and Celeste Watts, Denver's KMGH-TV reported. Further results from the laboratory were not released.

Christopher Watts is being held at the Weld County Jail on suspicion of murder. He is due back in court next week where he is expected to be formally charged in the deaths of his wife and two daughters.

The Associated Press contributed to this story.