LITTLETON, N.H. — There are a few fleeting minutes — just moments really — as Fred Murray rises in the early morning when the darkest of nightmares is banished to the corner of his consciousness.

“I wake up. It takes just a few seconds and then it crosses my mind,’’ he said. “I’m aware. It hits me. It’s a constant pall. To tell you the truth, it really isn’t any better than it ever was.’’

Thirteen winters ago, his youngest child, Maura Murray, crashed her clunker of a car, a 1996 Saturn, on a sharp turn on Wild Ammonoosuc Road in nearby Woodsville.

The 21-year-old Hanson native apparently lost control, slamming into a snowbank. When a passerby stopped and offered help, Murray, then a junior at the University of Massachusetts Amherst, waved him off. She told him that AAA road service had been summoned. All set, she said. The man, who lived nearby, drove off and called police anyway.

Seven to 10 minutes later, when the cruiser arrived, Maura Murray — a straight-A nursing student, a standout athlete, a former West Point cadet — was gone. Like the central character in a bad made-for-TV movie, she’d vanished without a trace.

There were no footprints in the snow. A heat-seeking helicopter, skimming treetops, spotted nothing. Search parties came up empty. Tracking dogs lost any scent within 100 feet of where her car sat abandoned by the side of the road in the White Mountains on that February night in 2004.

“She was a beautiful kid,’’ her father, who grew up in Weymouth, said. “She never caused me one bit of a problem — never caused anybody one bit of trouble in her entire life.’’

And now, as his daughter’s disappearance — once front-page news — has faded from the public’s memory, Fred Murray’s entire life is dedicated to finding her, to bringing her home, to assembling confounding pieces of a puzzle no one has solved.

“The case has to stay alive,’’ he said. “That’s the only hope I have. I can’t help Maura now. The only thing I can do for Maura is to grab the dirt bag who grabbed her. That’s all I can do. I must find her and bring her home.’’

And that’s why he was here last weekend, flanked by two of his children in a spare VFW post function room, as some 50 people — who have followed the case with the intensity of nuclear fusion — listened to a presentation of the facts laid out by a former cop and private investigator who has pursued the case nearly from the beginning.

Inconsistencies are examined and debated. Peripheral characters are sized up. Nettlesome questions — was the police response vigorous enough? — are raised in fruitless pursuit of answers.

Fred Murray had dinner with his daughter in Amherst on Saturday, Feb. 7, 2004. They had been shopping for a replacement for the Saturn, which belched oily blue smoke from its tailpipe. Hours later, at 3:30 a.m. on Sunday, Maura was at the wheel of her dad’s new Toyota when she struck some guardrails in Hadley, causing $10,000 worth of damage. By Monday, Feb. 9, she had used her computer to search for directions to the Berkshires and Burlington, Vt. She withdrew $280 from her bank account, and e-mailed a professor that she had to miss some upcoming classes because of a (fictitious) death in the family. She told them she was needed back in Hanson. Instead, she stopped at a liquor store. A box of wine was found in her car. By 7 p.m., the locked vehicle was found in that snowbank near a stand of pine trees on Route 112.

“She vanished in what seemed like a blink of an eye,’’ John E. Smith, a former Littleton police officer, said from a lectern as a documentary film crew recorded the session and crockpots of meatballs and beans and plates of vegetables, fruit, and cheese sat on long tables in the back of the room.

As a soft snow fell outside, dozens of amateur sleuths pursued tangents and tried to make sense of a case that authorities consider an active missing-person investigation.

“It’s still an open case with periods of activity and [at] times it goes dormant,’’ Jeffery A. Strelzin, New Hampshire senior assistant attorney general, wrote in an e-mail on Monday. “There are no new updates to share at this time.’’

All of this is more than a mystery to Maura Murray’s brother and sister, Fred and Julie, who know details about their sister that have nothing to do with an abandoned crashed car and the absence of footprints in snowy woods.

“Maura was a great, great kid. Great girl,’’ said Fred Murray, 46, who works for a sign company in East Bridgewater. “She was talented in everything she tried to do. She wasn’t bad at anything. Be it schoolwork: She got straight A’s. Be it athletics: top-notch in everything she ever tried.’’

To Julie Murray, Maura was more than a little sister. Two-and-a-half years younger, Maura was Julie’s shadow. They played on the same teams. They raced each other over pine needles and wooded paths during cross-country meets.

“We were always pushing each other,’’ Julie told me. “We spent every waking moment together. She was very witty. Her SAT scores were through the roof. I always tell people that when I was a freshman at West Point, I would call back to her to help me with my homework. It’s true. Just unbelievably talented in every way.’’

Her siblings have spent 13 years searching for her. Thirteen years without phone calls or text messages. Thirteen years of birthday parties, holiday celebrations, and life’s milestone events — their mother, Laurie Murray, died in 2009 on Maura’s birthday — with an empty seat where Maura should have been.

“And there’s no answers,’’ Julie said. “There’s that constant churning of your brain like: Well, what if this happened? Or: What if that happened? There are not a lot of answers. Was the timing absolutely perfect for someone to be there on the spot and snatch her up and do something bad to her? What are the chances of that? So I try to weigh that with reality and common sense.’’

Her big brother believes something had upset Maura. She traveled to New Hampshire to get away from it all, sort things out. He has little time or patience for conspiracy theories or wild Internet-fueled speculation.

“There’s so many things that could have happened,’’ he said. “It’s going to take someone coming forward with a piece of information to solve it and it’s probably something simple. The likely scenario is that she got picked up by someone. Maura is very smart but she’s not street smart. She grew up in Hanson, Mass.’’

Thirteen years is a long time for anger and heartbreak, for resignation and resolve. And for something else: deep worry about the psychic toll all of this exacts.

“My dad’s 74,’’ Julie told me in a quiet hallway away from Saturday’s presentation. “I don’t want much more time to elapse without him knowing something. I want some answers for my dad’s sake. Somebody knows something. Somebody doesn’t just disappear literally without a trace. This case and my sister are in his every waking thought. It never leaves him. Thirteen years is long enough. We need some answers.’’

Part of the reason Fred Murray is still working is because his job in nuclear medicine at Falmouth Hospital forces him to focus. It forces him to concentrate on something other than the missing daughter he doted on and loved.

In his mind’s eye, Maura still lives, the little girl he picked up after practice, the young woman he hiked mountains with, the talented nursing student whose horizons were bright and boundless.

He remembers those days as the best of his life. “I knew I would never have enough money to give them anything really big,’’ he said. “So I tried to give them as many little things as possible and hope that, eventually, you’d add up all those little things and in some way it might equal a big thing.’’

It’s the credo of a father who’s never stopped giving, never stopped working — the words of a dad on a sacred mission, a painful labor of love, he intends to complete.

Thomas Farragher is a Globe columnist. He can be reached at thomas.farragher@globe.com.