GILLETTE, Wyo. (AP) — A jury has convicted a northern Wyoming man in the death of his girlfriend's 3-year-old son.

Joseph Nielsen, 22, was found guilty Thursday of first-degree murder for the death of Caiden Fedora.

Prosecutors say Nielsen caused Caiden's brain injuries while he was baby-sitting the boy on Aug. 6, 2016. The boy died a few days later at a children's hospital in Aurora, Colorado.

According to court documents, Nielsen told investigators the boy jumped from a coffee table and fell over a plastic dollhouse. But doctors said the boy's injuries — including bruises, fractured ribs and a fractured jaw — were caused by a much greater force.

Nielsen's sentencing date has not yet been set.