LINCOLN — Tom Tanury stood atop a fire truck in the parking lot of the Lincoln Mall, overlooking a sea of motorcycles and their drivers, many of them clad in leather vests.

Bullhorn in hand, he told the crowd his speech would be short.

“I think you all know why we are here,” he said.

On the fire truck’s windshield were two copies of a poster that said “MISSING” in prominent letters. Below that was a picture of a smiling young woman, apparently taken in a portrait studio. Her hair was up, she wore earrings, and her turtleneck shirt was adorned by a necklace.

Katherine N. “Katie” Corcoran, 35, of Great Road in Lincoln, was reported missing 19 days ago. On Sept. 5, the married mother of two boys, a 4 year-old and an 8-month-old, left Butler Hospital, where she was receiving treatment for postpartum depression.

The Lincoln police said she took a cab to the Crossroads shelter on Broad Street in Providence, but never went inside. A woman believed to be Katie was sighted in several locations in Newport more than a week ago. But since the last sighting, last Monday, there haven’t been any new leads.

“I think Katie is the most popular girl in Southern New England,” Tanury told the group, speaking through the bullhorn. “She’s out there somewhere. We’ve just gotta find her.”

Tanury, along with Michael Akkaoui, president and CEO of Tanury Industries, have been leading the volunteer search for Katie.

Katie’s husband, Rob, works for Tanury’s metals finishing company, which applies precious metal coatings to items such as jewelry, airplane parts and high-end pens.

Yesterday morning, the search for Katie brought Tanury and Akkaoui, and several Tanury employees to the Lincoln Mall, seeking the help of hundreds of motorcyclists. The bikers were about to depart on an annual “Poker Run,” sponsored by the Vengeance Motorcycle Club.

Riders pick a playing card at each of the five stops along the run; the person with the best hand at the last stop wins a $150 prize. The $20 fee for tickets helps raise money for the club, and sometimes for various charities, said Dave Madison, president of the club.

Tanury had heard about the ride and contacted Madison to see if he could hand out flyers to the riders.

Madison said he was more than willing to help. “The more people who aware of her plight, knows what she looks like, there’s a greater chance of seeing her somewhere and she’ll be found,” he said.

Tanury also contacted the Tri-Boro Corvette Club and persuaded Ernie Boisvert, president of the club, to hold the club’s regular gathering of Corvette owners at the mall also. Someone in the club knew Katie’s husband, Rob.

Rob Corcoran was in the parking lot, too, and never seemed to be alone. Well-wishers, friends and coworkers continually approached him to offer a handshake or a hug.

“It’s overwhelming how supportive people have been through this whole process,” Corcoran said in an interview. “Words can’t describe how much this has meant to the whole family.”

Asked whether he had any idea why Katie would leave, he said, “I don’t think she’s running. She’s suffering from a mental illness. We believe it’s postpartum related.”

He said that she had been seeking treatment for postpartum depression for the past five months. The couple had made plans to go to California to seek additional treatment, he said.

“It’s devastating,” he said. “Too much to bear at this point.”

Shortly after Tanury climbed down from the fire truck, some 600 motorcycles, one and two at a time, roared out of the mall parking lot, heading for various destinations in Smithfield, Glocester and North Smithfield.

Tanury, 60, said he became involved in the search on day one.

“Katie is just such a special lady,” he said. “We’re not talking about someone who is a druggy or an alcoholic. This is not a domestic violence situation. It’s just one of those things that happen in life.”

Tanury created and had printed thousands of “missing” posters; he’s organized searches with volunteers; set up a 24-hour hot line that he answers himself; sent out e-mail blasts; started telephone campaigns; interviewed people who offered leads; scanned through surveillance videotape from a bus stop. He also hired a private detective, who has been on the case for two weeks.

“We’ve done everything we can possibly think of,” he said.

On Saturday, Akkaoui and a group of volunteers drove to the Port Authority in New York City on a tip that Katie might have been taken a bus to Manhattan. A RIPTA bus driver said he gave a ride to a woman whom he believed could be Katie, from Newport to Providence. The woman had been inquiring about where to catch a bus to New York. Akkaoui said that in New York, an ex-police officer took him and the group to shelters within a mile of the Port Authority. They didn’t find any evidence she had been there.

Akkaoui has been serving as a family spokesman for the Corcorans. There are two theories about where Katie might be, he said. One is that she is still delusional and wandering around somewhere. The other is that she doesn’t want to take her medication and that she’s trying to recover through prayer. Before having their last child, she was perfectly normal, he said.

Since her disappearance, Tanury said, finding her has become his full-time job.

“All of a sudden, my life was changed 19 days ago,” he said, “and this has been my focus.”

“Mike, also, just jumped in, right from the first hours we knew she was missing. We just felt as though we’ve got to do this.”

He seems somewhat perplexed when asked what prompted him to get so involved, rather than leave the search efforts to the authorities.

“When somebody’s in trouble, shouldn’t you help?” he said. He said he has two daughters, about the same age as Katie, and one of them is pregnant.

“I can’t imagine me going home and watching football games and baseball games and allowing [Rob] to deal this on his own.”

“We’ve got to find this girl and she needs our help. It’s just the right thing to do.”

Corcoran family and friends are offering a $50,000 reward for information that leads to Katie’s return home. Akkaoui said that anyone who sees her should not approach her. Rather, they should contact the police. The 24-hour tip line set up by Tanury is (401) 439-7988; the Lincoln Police can be contacted at (401) 333-1111.

tbarmann@projo.com