A Missouri man could face the death penalty following an alleged rampage in which he fatally shot and then burned four family members and a dog — whose bodies were all found at his rural residence in February 2016, PEOPLE confirms.

Grayden Lane Denham, 25, has pleaded not guilty to the four charges of first-degree murder that he faces.

Mark Gibson, the assistant prosecuting attorney of Platte County, in northwest Missouri, filed a motion this week to seek the death penalty if Denham is convicted. The motion was on behalf of the county prosecutor, Eric Zahnd, who declined additional comment to PEOPLE through his spokesperson.

Denham is accused of shooting and burning his grandparents, his sister and her 3 month old baby

Authorities discovered the bodies of Denham’s relatives on Feb. 20, 2016, at his residence in Edgerton, Missouri, after responding to reports of a structural fire, according to a probable cause statement obtained by PEOPLE.

Dead and lying in the front yard were his 81-year-old grandmother, Shirley Denham; his sister, Heather Ager, 32; and Ager’s 3-month-old son, Mason Schiavoni.

Platte County sheriff’s deputies — who found the home “fully engulfed in flames” — also discovered the dog dead in the yard, according to the prosecutor’s office.

The body of Denham’s grandfather, 82-year-old Russell Denham, was found near an out building east of the house.

All had been shot and were still on fire, authorities say.

Denham was missing from the residence along with his grandparents’ vehicle, which he was barred from driving because his license had been revoked due to points violations and child support enforcement, according to court documents.

PEOPLE.COM