Missing Hiker: Officials Scale Back Search As It Enters Day 6

PLEASANTON, CA — Law enforcement officials on Thursday afternoon scaled back the hunt for missing hiker Philip Kreycik, despite a promising report that Sunol residents heard someone calling for help late Tuesday night.

Thursday marked the sixth day of the search for Kreycik, a 37-year-old Berkeley ultramarathon runner and father of two who was reported missing by his wife Saturday afternoon after he failed to return from an hourlong run at Pleasanton Ridge Regional Park. Volunteers planned to search along the road outside of the park Thursday, in case Kreycik made his way out of the park.

Hundreds of volunteers and search and rescue personnel have scoured more than 50 square miles in the area of a loop he planned to take. They have braved rattlesnakes and difficult terrain by foot, horse, plane, e-bike and off-road vehicles, using search dogs, drones and heat-detecting technology. The search has so far turned up no sign of Kreycik.

Someone reported hearing a cry for help on Tuesday at the Sunol end of the park, in the opposite direction from the Moller Ranch staging area where Kreycik left his phone and car. Officials and volunteers searched the area Wednesday but found nothing, said Sgt. Ray Kelly of the Alameda County Sheriff's Office in a news conference that afternoon.

Officials believed they have exhausted all options in the park and will wind down search efforts. Areas around the trail Kreycik planned to take have been heavily trafficked by searchers. Kreycik is most likely incapacitated or no longer in the area of the park, law enforcement officials said.

Search and rescue crews on Wednesday saved one community volunteer suffering heat exhaustion.

"People are starting to get tired," Kelly said. "People are starting to get fatigued."

About 60 search and rescue personnel were at the scene Wednesday — half the number of people who worked Tuesday. Officials on Thursday will transition into a recreational search and rescue approach, which means they'll analyze data then strategically decide which points should be searched again, Kelly said.

A person can generally live a little more than four days without water — less with exposure to direct sunlight, Dr. Claude Piantadosi of Duke University told NBC News.

Meanwhile, the Pleasanton Police Department continued its missing person investigation. Officers have begun interviewing colleagues, friends and acquaintances and have focused on establishing Kreycik's timeline, Lt. Erik Sillaci said. Police believed Kreycik shipped a return package in Oakland before presumably heading to the park.

Police are interested in speaking with anyone who may have seen or heard from him in the hours immediately before he was reported missing at about 2 p.m. Saturday.

Kreycik was described as white with a thin build and brown hair and eyes. The public can contact police at 925-931-5100.

The search has been difficult and unprecedented in Alameda County, where missing people are generally found within a day, said Ron Seitz, volunteer chief of Alameda County Search and Rescue. It's especially unusual since Pleasanton Ridge is such a popular park, and it's likely that a passerby could have offered help.

Kreycik is a fit and friendly hiker and runner, a legendary outdoorsman who's well-known in the Bay Area and Harvard University community for his "huge, jaw-dropping adventures," said Tom Wooten, an organizer of the volunteer search and Kreycik's former college classmate.

Kreycik works as a strategic analyst of clean energy transportation at Pacific Gas & Electric Co., according to his LinkedIn profile.