A judge has ruled that a man accused of killing his 4-year-old nephew with an ax is not mentally competent to stand trial.

After a hearing, Broomfield District Judge Michael Goodbee committed Emanuel Doll, 25, to the Colorado Mental Health Institute in Pueblo, where he will be treated until such time as he is deemed fit to stand trial in the April 27, 2017, slaying of Jace Higginbotham.

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Doll was charged with two counts of first-degree murder in the slaying, one alleging that he killed the boy after deliberation, one alleging that he was in a “position of trust.”

According to previously released court documents, Higginbotham was summoned to the basement of his grandparents’ Broomfield home, then attacked and killed.

<p>Jace Higginbotham</p>

Higginbotham’s mother is Emanuel Doll’s twin sister, according to court documents and public records previously obtained by 9NEWS.

According to affidavits for arrest and search warrants, the boy’s grandparents, identified as Joseph and Charlotte Doll, picked him up at his mother’s home and returned to their house in Broomfield about 8:30 a.m. on April 27.

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For a time, the boy played with his grandmother in a main floor living room.

Joseph Doll told investigators that Emanuel – who lives at the home – went to the basement and a short time later asked the boy to join him. Charlotte Doll told investigators that around 9 a.m. she heard loud noises coming from the basement and yelled downstairs to Emanuel to ask what was going on.

“Nothing,” Emanuel Doll replied, according to the documents.

After Emanuel Doll went outside through a back door and then returned, Charlotte Doll went downstairs, where she found the boy dead on the floor.