The body found Sunday in a vehicle submerged in a Northern California reservoir is “likely” that of Kiely Rodni, local sheriff’s officials announced Monday, following a sweeping, 16-day search effort for the missing teen that involved what one law enforcement official called an “astronomical” number of resources.

While authorities could not “positively identify” the remains found inside a silver Honda CR-V pulled from Prosser Creek Reservoir on Sunday, Nevada County Sheriff Shannan Moon said officials believe the body was that of the 16-year-old Truckee girl who had disappeared earlier this month from a large party several hundred feet away from the discovery site.

“We recovered the vehicle last night,” Moon said during Monday’s news conference in Truckee. “We have located a decedent inside the vehicle. We believe it is our missing person. We have not been able to positively identify, but it’s more than likely.”

Authorities said an autopsy would be performed Tuesday, as well as a toxicology report. Results from those findings could take six to eight weeks to be completed.

Asked at Monday’s news conference whether there were any signs of foul play, Capt. Sam Brown of the Nevada County Sheriff’s Office said authorities could not comment on that possibility at this time. But Brown also said he had “no reason to believe” the vehicle had been anywhere else but the water since Kiely’s disappearance.

Officials said the FBI is evaluating the vehicle and assisting in that phase of the investigation.

A volunteer team of divers on Sunday said it had located the vehicle and presumed body of Kiely Rodni, as law enforcement officials and volunteers undertook a vast search campaign for her. Authorities had spent nearly 20,000 hours searching the area. Investigators received more than 1,800 tips regarding Kiely’s disappearance.

Adventures with Purpose announced in a Facebook post that its team of divers searching in Prosser Creek Reservoir found Rodni’s vehicle upside down in 14 feet of water with a body inside the silver Honda CR-V. The diving group said it had been in the water using sonar boats for 35 minutes when they located the vehicle 55 feet offshore and less than a quarter-mile south of the campground.

Kiely disappeared around 12:30 a.m. on Aug. 6 after attending a party of 200 to 300 teens and young adults at Prosser Family Campground, north of Truckee and located within Tahoe National Forest, according to Placer County Sheriff’s Office and Nevada County Sheriff’s Office.

The recovery area was about a quarter-mile south of the main campground area and roughly 700 feet from a dirt road that rings the reservoir.

Adventures with Purpose is an “underwater sonar search and recovery dive team helping families locate missing loved ones underwater,” according to its verified Facebook page.

Sheriff’s authorities announced Kiely as a missing person the same day she disappeared. The following day, the teen’s mother, Lindsey Rodni-Nieman, spoke out in a video posted by the Placer County Sheriff’s Office. Through tears, she pleaded for help in locating her daughter.

The Sheriff’s Office provided multiple updates each day in the immediate aftermath of the teen’s disappearance, urging anyone who might have information about the girl’s whereabouts to speak out and setting up a line for anonymous tips.

A reward established for finding Kiely rose to $50,000, then again to $75,000.

Early in the search, a Placer County Sheriff’s Office spokeswoman said the disappearance was being investigated as a possible abduction because her vehicle was unaccounted for, though the California Highway Patrol never sent an Amber Alert because it was not a confirmed abduction.

Kiely’s phone last sent a signal at 12:33 a.m. Aug. 6, sheriff’s officials said.