Either 37-year-old Philip Kreycik disappeared himself and doesn't want to be found, or he somehow got hurt or incapacitated in a part of an urban park that hasn't yet been searched, and investigators in Pleasanton continue to say they've never had a case nearly this bizarre.

A mystery now almost two weeks old continues to stump the detectives on the case, as volunteers and Kreycik's family continue search efforts that have so far yielded nothing but dead ends and frustration.

"Philip certainly comes from an incredible loving and resilient family who continue to be committed to bringing him home," writes one of the volunteers on a Facebook Group dedicated to the search effort. "All of the volunteers and members of this Facebook group and beyond have stepped up in so many ways, and his family and friends are incredibly grateful to all."

Volunteers and members of Kreycik's family gathered on Wednesday evening for a barbecue and some downtime, but investigators scaled back the official search last week due to a lack of any compelling leads and a thorough scouring of Pleasanton Ridge Regional Park, where he went missing on the morning of July 10. He told his wife he was going for a run, called her when he arrived at the park's parking lot to say it would take an hour, and then failed to meet up with her at a family gathering in Stockton two hours later. He left his shirt and cellphone in the car, and was running with a smartwatch that was not equipped with GPS.

Speculation immediately began that Kreycik might have become incapacitated by the heat — with temperatures having soared above 100 in Pleasanton that day. But as the Chronicle reports, Kreycik was a mega-marathon runner and was well experienced in exercising in the heat.

Also, the phone showed evidence of Kreycik's planned route, which was entirely along well manicured and maintained trails. And the park was hardly empty that weekend, but no one has reported any credible sightings of Kreycik.

Per the Chronicle, the area has been searched on foot and searchers have rappelled into a ravine — where a found t-shirt scrap turned out not to be a match for Kreycik's clothing. Carcasses of animals killed by mountain lions have been found. And for four nights after Kreycik's disappearance, an airplane flew overhead with a thermal-imaging camera capable of detecting body heat, but came up with no signs.

Investigators have not abandoned the possibility that Kreycik is still somewhere in the park in an area that hasn't been searched, but they say that possibility is getting less and less likely. When the official search was scaled back, Sgt. Ray Kelly of the Alameda County sheriff’s office gave a press conference and announced the other possibility, which is "he's not there."

There could also be some criminal element to Kreycik's disappearance, but Sgt. Aaron Fountain with the Pleasanton Police Department says there are "no indicators" of that. And, Fountain says, the whole case is "baffling."

"I can’t even speculate on this one — it’s very, very odd," he tells the Chronicle.

Kreycik, a father of two small children, is a graduate of Harvard and was listed as a third-year student in MIT's Urban Mobility Lab.

Kreycik's father, Keith Kreycik, remained hopeful that his son is still alive in speaking to KRON4 this week.

"He’s an incredibly strong guy and if there’s anybody who can make it out of the woods he will and in fact he may have already made it out of the woods," he said.

Previously: Search For Missing Berkeley Runner In East Bay Canyon Enters Fifth Day