PLEASANTON (CBS SF) — A massive weekend search effort failed to uncover any new clues as to the fate of Philip Kreycik, a jogger who was believed to be missing in Pleasanton Ridge Regional Park since July 10th.

Sgt. Ray Kelly of the Alameda County Sheriff’s Office echoed the growing frustration surrounding the search in a news release Sunday night.

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“We truly feel we have done an enormous effort covering all possible scenarios during the past eight days,” Kelly said in a Facebook post. “Like the community, we are frustrated and perplexed that this massive effort has yielded no results. We feel we should have found Philip by now.”

Missing: Philip Kreycik

Philip Kreycik. (family photo)

On Sunday morning, a team consisting of 169 professional searchers, 10 law enforcement officers and 8 fire department personal joined family members in the largest effort to date.

“We re-checked areas we had searched before that had limited access,” Kelly said. “We wanted to go back in to those difficult areas to be 100% sure. These areas included deep ravines with high angle rope teams traversing the steep terrain. We also searched private property areas, adjacent park land, to make sure we were exhausting every possible scenario.”

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Authorities also “followed up on 72 hours worth of tips and leads that came in from police and community reports.”

Searchers did find a partial tee shirt in a ravine, but family members verified it did not belong to Phillip.

“Phillip is still missing and we want to find him,” Kelly said. “If you know anything or have any information please contact the Pleasanton Police Department.”

Kreycik went missing on July 10 when he didn’t show up for an appointment after a pre-planned eight-mile run in at the park. His car and phone were located at the trailhead.

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Hundreds of searchers have joined efforts to find the 37-year-old Berkeley resident over the last nine days.