Heartbreaking new details have emerged in the case of the missing Florida boy who was found dead next to his dog as his father faces charges for allegedly making explosives.

Johnathan Boley, 4, did not show any signs of “trauma or assault type injuries” after officials performed an autopsy on Monday morning — three days after the heartbreaking discovery, according to Walker County Sheriff Nick Smith.

A cause of death has not been released as officials await the results of further tests, WBRC reported.

Boley, known by his family as “John John,” was discovered partly in a body of water by a group of volunteers who were searching the wooded area in Jasper, Ala. — two miles from where the boy vanished.

The child, who was visiting his father for the holidays, was last seen playing in the yard with his older brother and their mixed lab pup Buck just before noon on New Year’s Eve.

Boley’s elder sibling said his brother and the Buck had walked across the property line. Jameson Kyle Boley reported his son missing an hour later.

The little tyke, who lived with his mother in Florida after his parents separated, was discovered just before 1 p.m. Friday.

Buck, the loyal pooch, was found alive and next to Boley’s body.

Volunteers were “shook up” when they found Boley after the days-long search.

“You know, obviously you come out to do a good deed and when you get our there, you may have thought that you have fully prepared yourself for what you might come across,” Smith said. “Obviously, they were shaken up.”

Officials also discovered explosive materials inside and around the elder Boley’s home. The discovery of the potentially dangerous materials forced officials to cancel a ground search in the area.

Methamphetamines were also discovered inside the home.

Officials found “evidence that they have had some type of bomb type materials and that have exploded on the property.”

Boley, 40, was arrested and charged with unlawful manufacturing of a destructive device and two counts of chemical endangerment of a child.

He was transported to Blount County jail to “keep him separated from the county and people he may know in the jail,” Smith said.

After “John John’s” body was recovered, family members were permitted to go to Blount County and share the devastating news with the jailed father.

“I arranged with the sheriff of Blount County to let the family go make that notification in person,” Smith said.