(CNN) -- A petition demands the Wisconsin Department of Corrections remove photos that convicted murderer Chris Watts put up in his cell of his victims.

The photos are of his pregnant wife and two young children.

"As taxpayers and members of the public, we are outraged that Chris Watts was allowed to have a photograph of the victims he was convicted of murdering, including his two minor children," the petion, found on Change.org, reads.

"Allowing a murderer to keep a trophy of his victims goes against the purpose and mission statement of the Wisconsin Department of Corrections, which emphasizes public safety and victim advocacy. We, the public and taxpayers, demand that any pictures of Watts' murder victims are confiscated and that he does not receive favorable treatment due to the publicity of his criminal case."

In August, Watts killed his wife, Shanann, 34, and their two children, Bella, 4, and Celeste, 3, before disposing of their bodies at a secluded oil field where he worked.

He pleaded guilty to the killings last last year and is serving five life sentences after prosecutors and Shanann Watts' family agreed to drop the possibility of the death penalty.

READ MORE: Here is all of Denver7's coverage on the Chris Watts case

The revelation about the prison cell photos came after the Colorado Bureau of Investigation released notes from an interview its agents had conducted with Watts earlier this year.

"He has pictures of his wife and daughters in his prison cell and he talks to them every morning and every night," reads the document, in which Watts gives a detailed account of the killings.

The petition, which so far has amassed more than 5,000 signatures, wants the photos returned to the victims' family.

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