He walked out the door with his keys and wallet. That's how it started.
Jerry Tang was a handsome, creative tech executive who played jazz piano, volunteered at his church and doted on his wife and two boys, ages 4 and 7.
Then, on Nov. 29, he was gone.
The San Francisco man is one of more than 4,000 people who are reported missing yearly in this city alone -- though most cases are resolved quickly. But Tang's disappearance has prompted a grass-roots search campaign so thorough that police and private investigators call it unprecedented.
Friends, family and strangers have scoured homeless shelters, stood on street corners with massive banners and checked encampments from Golden Gate Park to the remote beaches of Marin County.
Childhood buddies have flown in from as far away as London to help, visiting shelters and bus stations in the Bay Area, Las Vegas and Tang's home state of Massachusetts.
At the request of a friend of Tang's, the Craigslist website promptly agreed to post "find jerry" links on every page, drawing in sympathizers who never met the man but are touched by the story of his disappearance.
Tang's gentle smiling face now beams from "missing" posters on telephone polls throughout San Francisco, and his name is widely known here.
"His family and friends have come together in ways I've never seen before," said San Francisco Police Inspector Andrea Martin. "They've been through the city like wildfire."
So pervasive is the effort that a private investigator approached by the family declined their money, saying he could do nothing they had not already tried.
The search for Jerry Tang, who suffered a stroke almost three years ago at 37 and was depressed about his ongoing seizures, has become a parable of community connection, hope and sudden loss.
His friends and parents -- Taiwanese-born immigrants -- believe Tang could be wandering the streets with amnesia or an altered thought process triggered by another stroke or seizure (he left home without his medication).
It is their best hope, the only scenario that adds up while still keeping Jerry among the living. They have spent dozens of hours developing rapport with homeless men and women who have tipped them to possible sightings.
There was a tall Asian man with a shopping cart resting in a downtown nook. Another in the food line at the St. Anthony Foundation. Yet another lingering by the city's ragged bus terminal. The tips turned up nothing. But they are leads that can be followed. And action equals hope. Early last week about 60 supporters gathered in the small San Francisco church where Tang and his wife, Joyce, are members. They were there to celebrate Tang's 40th birthday. The congregation has poured out its support, as have parents from the Tangs' nearby elementary school, cooking meals for Joyce and the children.
On this rainy night, Tang's family announced a $10,000 reward, half from his parents and part from Jerry Tang's partner in the San Mateo tech start-up, Smalltown, where he was working long hours before he vanished.
The participants sang "Happy Birthday to You" -- marked by quiet sobs -- then lighted candles for Tang's safe return.
"Those of us who know him have a hard time accepting that he could have the ability to come home and hasn't," reasoned one longtime friend, Ingrid Overgard. "It's not the Jerry we know."
The Jerry they know, said Los Angeles attorney and high school friend Ed Hoffman, is "a gregarious, good-natured guy with a good sense of humor. I never remember Jerry having a harsh word for anybody."
Tang grew up in Framingham, Mass., then married his college sweetheart. His friends stuck with him for years and now nourish Tang's parents with small surprises: stories about the times Tang bought lunch for the homeless, how he befriended an aging blind man and regularly read aloud to him.
Then came the stroke. It didn't change Tang. He was always spiritual and sensitive -- a soft-spoken "deep thinker," said his father, Jeffrey Tang. But grand mal seizures followed. And the medication drained him.
For the first time, family members said, Jerry Tang seemed to struggle. Working on the start-up -- and an outlay of his own cash as the company awaited venture capital -- proved stressful too, his father said.
"He had become very weak and very tired," said Jeffrey Tang, 71, who, with his wife, Julia, moved to the Bay Area retirement community of Rossmoor in 2004 to be closer to Jerry Tang and his two siblings, Audrey and Austin.
On Nov. 29, the 6-foot-1 Tang canceled a doctor's appointment, then told his office that he was feeling too ill to come in. He spoke to his wife by phone at 10 a.m. That's the last anyone heard from him.
Tang is believed to have been wearing a blue nylon jacket, blue jeans and brown New Balance shoes. His credit cards and cellphone have not been used since.
Numerous reports placed a man who matched his description sitting forlornly on a Golden Gate Park bench in a downpour. A groundskeeper offered him an umbrella. Law enforcement teams searched the park for days and dragged the bottom of its largest lake.
The possibilities that Tang intended to disappear or may have killed himself remain open, though police efforts to locate him remain active.
"Mr. Tang did cancel an appointment that he had. He did say that he was not going to work," said Martin, the missing-persons detective. "When you hear that a person has at least a short-term plan not to do what he was going to do, you have to think: What was in his mind to make him not do something the normal way that day?"
But Tang's family and friends cannot linger on those thoughts. Psychics have pictured him on a street, lying in a garden, on a beach near a windmill.
His disappearance triggered a viral response as e-mail lists begat e-mail lists. A Yahoo listserv keeps 200 of his closest friends informed. Another public website -- www.findjerry.org-- draws tips and ideas from hundreds more.
Strangers, too, are spreading the word.
"This really has struck me," wrote one on a family blog. "This man is one of those 'upstanding' citizens, a good father and husband, a high-tech executive, a neighbor ... and then suddenly he is roaming the streets.... But for fate, there go I."
Tang's family is also humbled by the response.
The day after Jerry Tang's birthday, his father took the train to San Francisco and walked the gritty blocks past addicts and drunks to the San Francisco Rescue Mission. There, he prayed for Jerry and participated in a Bible study.
"You know, I talk to many homeless people," Jeffrey Tang told Pastor Ralph Gella and a small gathering. "Many of them express concern. They volunteer to show me around. Even though their physical condition is poor, they still have righteousness."
The session over, Jeffrey Tang asked the men if they had seen a volunteer known as "Boston." The man from Massachusetts had told Jeffrey Tang a week before that he believed he'd seen his son. But on this day, "Boston" was missing too.
With a laminated missing-person poster of Jerry pinned to his shoulder bag, Jeffrey Tang then made his way to a financial district building where Tang worked four years ago.
The company is long shuttered, and another has replaced it. But the security guard accompanied Jeffrey Tang upstairs so he could search the unlocked sixth-floor bathroom.
"It's a longshot. I don't know what I'll find. But I just want to be clear in my mind," the elder Tang explained.
"I am trying to generate some hope."