COLORADO, USA — Thousands of people have joined a petition asking for more criminal charges in the case of Kelsey Berreth’s murder.

The Woodland Park mother was last seen on Thanksgiving Day. Patrick Frazee, who had a relationship and a child with Berreth, is now charged with her murder.

An Idaho woman was also involved in this case.

Krystal Kenney told investigators Frazee solicited her to kill Berreth three different times. When she did not commit the crime, she told police he did it himself. Investigators said Kenney admitted that she helped clean up the crime scene and cover up evidence.

In February, Kenney pleaded guilty to tampering with evidence, and agreed to cooperate with prosecutors in the case against Frazee.

An petition that started online at change.org calls for more charges in this case. It asks the U.S. Attorney’s Office and the Federal Office of Violence Against Women to charge Kenney – and any of her friends who may have had knowledge about the crime – with Conspiracy to Commit Murder.

The petition has gathered more 2,400 signatures. KOAA reports the group of concerned citizens who helped start the petition submitted it into the U.S. Attorney’s Office on Wednesday.

Jeffrey Dorschner, a spokesman for the U.S. Attorney’s office, confirmed the petition was received but would not comment on the case.

9NEWS legal analyst, Scott Robinson, said federal intervention is unlikely.

“Citizens have a right under the constitution to petition the government with grievances, but it’s probably not realistic to think a federal U.S. Attorney is going to prosecute a murder case that’s being prosecuted already by state authorities,” he said.

“Colorado does have an obscure statue that does permit people to file a lawsuit to force prosecutors, [specifically] District Attorneys, to pursue criminal charges. To my knowledge, none of those very rare suits has ever been successful.”

As part of her plea agreement, Kenney won’t receive a sentencing until after the case with Frazee concludes.

“I understand why citizens are up in arms, it does seem like Krystal Kenny’s been given an awful lot of benefits despite the fact that she actively assisted in the covering up in this heinous crime,” Robinson said.

“But prosecutor Dan May really needs Krystal Kenny, with no body [of the victim], he needs to have [Kenney] tie together the other evidence.”

“There’s nobody more important to the prosecution than Krystal Kenny in the case against Patrick Frazee.”

SUGGESTED VIDEOS | Local stories from 9NEWS