Prosecutors in the Chris Watts murder case are seeking the suspect’s footprints, reportedly for comparison to evidence found at the crime scene.

Watts was arrested last month and charged with the murder his pregnant wife Shanann Watts and their daughters Bella, 4, and Celeste, 3. The bodies of all three victims were found on the property of the petroleum company in Colorado where Watts worked until the week of his arrest. He reportedly confessed to killing his wife, but claimed he did so in a “rage” after seeing that she allegedly strangled their daughters.

The charges filed against Watts indicate that investigators do not believe his claims about Shanann’s role in the killings.

The Denver Post obtained court documents filed Tuesday which show that the District Attorney’s office has asked for the suspect’s inked footprint impressions.

Weld County District Attorney Michael Rourke reportedly wrote in the motion that “possible bare footprints” were found at the murder scene among “items of evidence” which the motion did not specify.

Previously, attorneys for Watts’s defense had asked the court for DNA samples from the necks of Bella and Celeste, but a judge reportedly denied the motion, stating that the court did not have the authority to direct the coroner’s investigation.

Authorities have not officially announced the precise cause of death of the three victims, though reports about the ongoing investigation do suggest that strangulation is being considered.