A cry for help reported by a couple in the area of Sunol Canyon on Tuesday turned out to be a dead end, as hundreds of volunteers continue to aid in the search for a Berkeley father of two who disappeared while on a run Saturday.

37-year-old Philip Kreycik of Berkeley remains missing and around 200 volunteers continue searching about 50 square miles of wilderness in the area of Pleasanton Ridge Regional Park in the hills west of Pleasanton. Kreycik, an ultramarathon runner, left his cellphone and shirt in his car around 10:45 a.m. on Saturday, intending to go on an eight-mile trail run that he often did in this park. His wife reported him missing when he did not return Saturday afternoon.

As ABC 7 reports, it was 106 degrees in Pleasanton at the time of Kreycik's disappearance, and speculation has already turned to the possibility that Kreycik became somehow incapacitated by the heat. But heat-seeking drones, canines, and the efforts of the many volunteers have still come up with no signs of Kreycik five days later.

Volunteers are braving some rugged terrain filled with poison oak, rattlesnakes, and more, as Pleasanton Weekly reports, but still so many volunteers showed up Tuesday — heeding calls from this Facebook Group and elsewhere — that organizers said they'd reached a saturation point.

The "heat map" below indicates places in the park that have already been reported searched.

On Tuesday, volunteers redoubled their efforts after reports of someone crying for help near one canyon, but this led nowhere.

What's been especially frustrating to authorities is that they say Kreycik left behind a map of his planned route on a running app on his phone.

If Kreycik survived, he would have had to have done so without water in triple-digit temperatures that continues into Sunday.

Searchers have found sheep and deer that were killed by a mountain lion or lions in the area, and at least one mountain lion sighting has been reported. Also, authorities say that a rock was found with blood on it, that blood was analyzed, and it was not human blood.

"We should have seen him by now, we should have encountered, there should have been something that led us to him, some type of something and that's what is hard to digest here," said Sergeant Ray Kelly with the Alameda County Sheriff's Department, speaking to ABC 7 on Tuesday. "That's why we're all here tonight it's hard to leave knowing that we haven't exhausted all those questions in our minds."