CHICAGO (CBS) — Preliminary results from the autopsy of an 18-year-old man who was reported missing and later found dead in a backyard pool in Waukegan has ruled out physical trauma, according to authorities.

A final ruling on the cause of death of Lucio Cambray was pending the results of toxicology testing and further investigation, according to a statement Friday from the Lake County Coroner’s Office.

Cambray, of Waukegan, was last seen Dec. 25, according to a statement from family and friends. After he dropped off his girlfriend earlier in the day, he was last seen by a friend who left him at a BP gas station at Jackson Street and Grand Avenue in Waukegan.

Family, friends and community members organized a search with police and the Missing Persons Awareness Network to locate Cambray.

His body was found about midnight Monday in a pool located behind a vacant house in the 1300 block North Jackson, Waukegan police and the coroner’s office said.

Though Cambray’s autopsy ruled out physical trauma, his relatives still suspect foul play in his death, according to Julie Contreras, a spokeswoman for the family.

“He didn’t just throw himself into a pool on a freezing cold day,” Contreras said. “The family believes there was foul play in his death and they continue to try and seek justice. We believe some people know more than they are saying.”

Contreras added that the family is “thankful” for the ongoing efforts of investigators.

On Wednesday, Contreras said that tips given to police by Cambray’s family led to several people being interviewed by authorities in connection with the missing persons case. That questioning led police to discovery of his body early Monday, she said.

Waukegan police spokesman Joe Florip declined to comment on how investigators found the body.

Cambray was living with the family of a friend in Waukegan when he went missing, Contreras said. His parents live in Mexico, but he has a sister, Odalis Cambray, who lives in Waukegan. His mother was expected to arrive Monday.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2018. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

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