Chris Watts, who murdered his family nearly three years ago, has spent his 36th birthday inside the prison. 

But one source, who regularly talks to Chris Watts, told People that the murderer is on the lowest social tier of the entire prison, with inmates and guards not talking to him. The source added that no one wants to do anything with him.

The person with knowledge on the matter further noted that Chris Watts, who turns 36 on May 16, is in protective custody since he's an outcast that would be in real danger if he's around other inmates.

The source dubbed Watts as the "most hated person in prison" because he killed children. The source noted that Watts could go for days without talking to anybody.

The source added that there is a definite order in jail that people who hurt or kill kids are at the "very bottom."

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Chris Watts Murdered His Family

Chris Watts has murdered his pregnant wife, Shanann, and their two children, four-year-old Bella and three-year-old Celeste, in August 2018. 

He pleaded guilty to the crimes in November of the same year. Watts said he took his wife and their children's bodies to an oil site and buried them after killing them.

Chris Watts is now serving a total of five life sentences in prison as Shannan Watts' family did not seek the death penalty in the case.

Authorities found out that Watts was having an affair with a co-worker, which led him to commit the murder. The said mistress allegedly said that she thought he was already separated.

Shanann's friends said they heard trouble in the couple's marriage. On Jun. 11, 2018, Shanann Watts announced that she is expecting another child again and surprised Chris with the pregnancy news. Watts was recalled to say that it was awesome.

In July 2018, Watts had started having a physical relationship with his then mistress, Nichol Kessinger.

Nichol Kessinger then started sending Watts seminude photos of herself, which he kept on a secret calculator app on his phone.

Chris Watts said that he was drawn to Nichol Kessinger because he felt that she was pursuing him instead of the other way around.

Watts and Kessinger reportedly visited Great Sand Dunes National Park, and they spent the night at a nearby campground. They did this while Watts was seeing Kessinger about four or five times a week, Biography reported.

Chris Watts had then told Nichol Kessinger that he was almost divorce. Later in July, his wife and their daughters went out of town in North Caroline. It was when Watts had told Kessinger that the divorce is final.

On Aug. 13, 2018, a missing-person poster showing the faces of Shanann Watts and their two daughters circulated. This was after they suddenly disappeared from their home in Colorado, according to an Insider report.

A day before he was arrested, Chris Watts had initially agreed to a TV interview, where he looked torn up and begged for his family's safe return. 

He was arrested on Aug. 15, 2018 after police discovered Watts has a mistress, and he failed a lie detector test. He then eventually admitted to strangling his wife and burying her at an oil site, where their kids' bodies were also found in two oil tanks.

Chris Watts earlier said that he hoped to appeal his sentence. But he has not filed any paperwork until now. 

READ MORE: Man Linked to Deaths of His Ex-Wife and 4 Others Admits to Killing 11 More

WATCH: Christopher Watts Sentenced to Life in Prison After Murdering Family - From Daily Mail