A few left their driver door open and motor running. One man pocketed his keys. Another wore a Superman T-shirt when he plunged nearly 200 feet into the mouth of Tampa Bay. One woman may have taken her dog with her. Another person wrote "sorry" and "time to go."An average of once a month last year, people committed suicide by falling from the Sunshine Skyway bridge, and authorities are trying to determine whether a 13th person also died that way.Not since 2003 have 13 people fallen to their deaths from the Skyway. In the years since then, at least 130 more followed, according to information provided by the Florida Highway Patrol and medical examiners offices in Hillsborough, Pinellas and Manatee counties.The last man to drop in 2017 was William Robeysek, 64, the morning after Thanksgiving, his family said. Troopers found his car on the bridge. A boater found his body on the first Sunday of December on an island about 5 miles west of there. Dental records showed it was him, but authorities await test results."I miss him terribly," said Ashley Stevens, 65, his girlfriend of 13 years. "I have no idea why he would leave me."Robeysek was unmarried, had no children and was recently placed on disability benefits. He didn’t leave a note.• • •Most last year did not leave notes. Those who did left many questions unanswered.The first to fall in 2017 died a year ago Friday. David Prior, then 55, worked as an investment adviser and had two children and a wife. Debra Prior, 53, said she and her teenage daughter suffer from post-traumatic stress disorder and avoid the bridge.Her husband left a note, but she still doesn’t know why he chose the Skyway."Maybe he thought it would be the fastest way to go," she said. "He used to jump out of planes in the army. He was a Green Beret Ranger."Two days before he went off the Skyway, David Prior was released from St. Anthony’s Hospital, where he had been committed under the Baker Act after slitting his wrists, his wife said. She’s suing the hospital, alleging negligence.Therapists have told Debra Prior not to attempt to figure out why he killed himself. "We are never going to know what was in his mind," she said. • • •Most suicide is a solitary act, often by gunshot or strangulation, said Frederic Desmond, a professor of psychology at the University of Florida. Falling from a high platform is less common.A public suicide attempt may be a last chance to reach out for human contact."It could also be a last-minute cry for help," he said. "They might hope that someone driving will stop them."Clara Reynolds, CEO of the Crisis Center of Tampa Bay, avoids publicly discussing Skyway suicides because she doesn’t want to plant ideas in anyone’s head."We want to have open conversations about why people contemplate suicide and we need it to be more socially acceptable for people to reach out," she said.The center gets thousands of calls each year from people contemplating suicide. A small percentage of suicides are from the Skyway, less than 3 percent in 2016.Special phones installed on the bridge in 1996 connect directly to the Crisis Center, but in 2017, only "silent calls" came through. The people on the bridge did not speak."They might be trying to make a last-minute connection with someone," Reynolds said. "It could be that they want someone to know they are up there."When someone uses one of those phones, the center’s staff alerts authorities. Officers stop at least five suicide attempts each year on the bridge. On Tuesday, a Pinellas deputy used his vehicle to pin a woman’s leg to the side of the concrete barrier, preventing her from throwing herself over. After he handcuffed her, she continued to say, "Let me jump, let me jump," the deputy said.Five of the deaths in 2017 were women.• • •Experts say suicide doesn’t solve problems, and often hurts those left behind.In May, Pinellas Park police charged Ryan Mogensen in the hit-and-run death of a motorcyclist, 61-year-old John Ryan.In June, Mogensen pleaded not guilty, but the case never went to trial.On a dark night in July, he leaped off the Skyway bridge. He was 28.The Pinellas-Pasco State Attorney’s Office formally abandoned the case.A medical examiner’s report describes a suicide note Mogensen posted on Facebook. He called himself a veteran and said he had been charged with a crime. He wrote that he loved his family and apologized to them.When John Ryan’s wife, Rosamme Ryan, 54, found out that Mogensen had killed himself, she initially took solace in the idea that he could not hurt anyone else, she said. But in the months since police found his body, her attitude has shifted."That night, it felt like justice," she said. "But the further away I get from it, I realize I’m never going to face him. I can never ask him why he hit my husband."Contact Jonathan Capriel at [email protected] Follow @jonathancapriel.