John Wirth of Petaluma had been lost a long time when police caught up with him in St. Helena late Thursday night, got him something to eat and drink, and brought him back home.

It had been more than 40 hours since the mentally disabled man had left on one of his usual bike rides, and clues from his ensuing odyssey suggest he may have pedaled as much as 60 miles along a sometimes treacherous route that included Highway 37 toward Vallejo, though there's no way to know for sure.

All he could tell authorities when his adventure came to an end late Thursday was, "I was just out for a bike ride," Petaluma Police Lt. Tim Lyons said Friday.

He was weary and worn, but "he was OK," Lyons said.

"There are no words that can say how grateful I am," said Wirth's sister, Mary Ann Grant. "I was so worried he wouldn't make it back."

Wirth, 48, suffered a traumatic brain injury in a near-fatal motorcycle crash 25 years ago and has lost his ability to perform many normal daily functions, Grant said.

The two moved north from Ventura County about a year ago to enjoy the relative peace and quiet of the North Bay, and Wirth enjoyed going out on his red bike each day from their Petaluma Way home near North McDowell Boulevard, often heading a couple miles down the road to McDonald's or Taco Bell, she said.

But Wirth had been venturing farther and farther, it seemed. He had recently been spotted cycling near the Kaiser medical center on Lakeville Highway, police Detective Joel Stemmer said.

"He doesn't really know the area," Grant said, "although I'm trying, little by little, showing him, 'You could do this. You could do that.'"

On Wednesday, Wirth left home at about 7 a.m. His sister had given him $10, Stemmer said.

He also took the flip-top cell phone that she had bought for him. Though Wirth didn't know how to use it, his sister hoped it might be useful if he ever became lost, Stemmer said. "It was more for a device to help locate him in case this kind of thing happened," he said.

Grant dialed it when Wirth hadn't returned home by Wednesday evening, calling the phone a few times, but he never picked up. She reported him missing to Petaluma police around 7:30 that night.

Investigators traced the phone signal to the Vallejo area, but it went in and out and only indicated a very general area, Stemmer said.

Unable to locate him further, police issued a news release about him late Wednesday that was distributed in part by Nixle, an internet notification service.

A Solano County sheriff's deputy who who saw it recalled having seen someone matching Wirth's description pedaling east on Highway 37 near the county line Wednesday afternoon and reported it to Petaluma police.

Another person who saw the release was a Rohnert Park police dispatcher who happened to drive to St. Helena on Thursday evening and, en route, saw a man walking a bike on northbound Silverado Trail.

Dispatcher Melissa Kositzin said it occurred to her that anyone pushing a bike on such a busy road might welcome a ride, but she decided to err on the side of safety. A few hours later, returning south from town, she saw him again and noticed he hadn't gone far.

But it wasn't until she was home in Petaluma and on her computer an hour or two later that she saw the Nixle alert again and connected it to man she had seen.

She called police around 10:30 p.m. just as a largescale search and rescue operation was coalescing near Jameson Canyon Road at the Napa/Solano county line, where the last cell phone signal had been detected.

Around that same time, Napa County authorities got a call from a resident who reported a suspicious man on Silverado Trail. A deputy was searching the area when Wirth appeared and asked if he could get a ride home, police said.

He'd lost his cell phone, and needed to eat and rest — he actually fell asleep on the ride to Petaluma — and wasn't able to say where he had been.

But he was safe.

"I asked him, when he got home," Grant said, "I said, 'Are you going to do this again?' He said, 'No!'"

(You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.)