An autopsy has found that a 6-year-old California girl whose burned body was found in a remote field 90 miles from her home died of a blow to the head.

Glenn County Sheriff Richard L. Warren Jr. said Wednesday that Jadianna Larsen of Sacramento suffered blunt-force trauma.

The girl's charred body was found May 28 off a country road in Glenn County.

Twenty-five-year-old Juan Rivera and his mother, 46-year-old Lisa Suzanne Burton, were arraigned earlier this month in the killing.

Prosecutors say Rivera killed Jadianna and Burton was an accessory after the fact. Rivera was the boyfriend of Jadianna's mother, Tanecia Clark.

Rivera told investigators he suffered a bout of seizures, and when it was over he noticed Jadianna was missing.

The Sacramento Bee reports (http://bit.ly/1ImlGtf ) Rivera and Burton will return to court Aug. 7.