The elderly man who disappeared from the Golden Pond assisted living facility on Sunday night and was rescued Tuesday morning never strayed that far from the grounds, interim Hopkinton Fire Chief Gary Daugherty believes, but because he was in a “very deep, thick area of brush and mud,” he was difficult to locate.

Jim Noon, 84, wandered away from Golden Pond on Sunday around 10 p.m. He is believed to have entered the woods behind Icehouse Pond — right next to the Golden Pond residence — and may have fallen into the brush soon after.

“I think in the middle of the night he tripped and he was there the whole time,” said Daugherty, who added that he walks the area himself. “That’s my speculation, just because there’s a lot of thick thorn bushes, it’s very hilly, it’s not an easy terrain to walk, especially without a flashlight or anything. … He wasn’t on a path. He was in the woods, between two creeks and a marshy area, surrounded by big thorn bushes.”

Daugherty was in the command post outside the Golden Pond facility to coordinate the search, which had resumed Tuesday morning after a pause due to heavy rain and darkness Monday night. He said the concern for the man’s safety escalated after the downpours.

“I was starting to get nervous there with the amount of time that went by and the weather the night before,” he said. “I was really getting nervous. Being wet all night, I was worrying about him getting hypothermic, being out in the environment for 36 hours, not eating, not drinking.”

The key to the discovery, Daugherty said, was a computer analysis.

“We searched that area the night before and during the day with dogs and drones, then we used some data that we have with a mapping program that takes the patient’s age, his medical history, all types of statistics from national searches, and it creates a cone from the last-seen point,” Daugherty explained. “We put all the data into the computer, and that projected his route of travel. Then we basically did a line search from the last-seen point through that cone, and that’s how they found him.”

Individuals from the State Police Special Emergency Response Team eventually located Noon about 138 yards from the Golden Pond facility, Daugherty said. Noon was “conscious and alert,” according to the State Police, and Daugherty said he was “talking a little bit.” Noon was in stable condition and was transported via ambulance to the hospital. No update on his condition was available Wednesday morning.

After some recent tragic endings to local searches, including this summer’s drowning at Sandy Beach, Tuesday’s positive outcome brought great relief to first responders.

Daugherty recalled the moment he got the call from the State Police that Noon was discovered. He said there was a little delay after the initial communication of “We found him,” as rescuers worked to determine Noon’s condition.

“As soon as we found him and we knew he was alive, there was a lot of excitement,” Daugherty said. “That was a lot of hard work for 36 hours by a lot of firemen and cops and troopers.”