WASHINGTON (CBSDC/AP) — The cause of death of a 7-year-old D.C. boy who was missing for nearly 36 hours is still unclear after a preliminary autopsy, police said.

The autopsy of Michael Kingsbury showed no signs of foul play or trauma, but authorities said at a press conference Tuesday afternoon that they’re “not ruling anything out.” Kingsbury, who was autistic, was reported missing Sunday morning and his body was found inside a vehicle near his Northeast D.C. home Monday evening.

The medical examiner’s office will conduct a toxicology report to determine that the cause and time of death, and police will continue its investigation, authorities said.

D.C. police scoured the city for nearly 36 hours before finding the autistic child on the rear passenger floor of a locked vehicle less than a block from his home in the 1700 block of West Virginia Avenue NE.

Police said the vehicle in which Kingsbury’s body was found had previously been looked into by at least four officers, as well as Kingsbury’s family. The 7-year-old’s body was found inside on the passenger’s side of the vehicle at about 6 p.m. Monday following another search, police said.

Police know who the vehicle belongs to but are not releasing that information to the public.

Katrina Kingsbury said her son was last seen Sunday morning wearing only a diaper near the family’s home in D.C.’s Trinidad neighborhood.

Officers canvassed the neighborhood and interviewed local registered sex offenders while searching for the boy. Family members were also interviewed by police.

Officers had earlier searched abandoned buildings and sheds.

WNEW’s Matt DelSignore contributed to this report. Follow him and WNEW on Twitter.

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