Photo: Change.org

Daniel Robinson

When there were few people helping David Robinson search for his missing son, he refused to give up.

On June 23, Daniel Robinson, a geologist, was reported missing after he was last seen leaving a job site near Sun Valley Parkway and Cactus Road in Buckeye, Ariz.,according to a press releasefrom the Buckeye Police Department.

Daniel’s cell phone, wallet and keys were found with the vehicle, andpolice statedthat “no foul play is suspected.”

But Daniel’s father says he and his family continue to have questions about his son’s disappearance.

“From the first day that I arrived in Phoenix, Arizona, I have done more to find my son than the law enforcement agency, whose jurisdictional authority covers where he was last seen and where his vehicle was recovered,” Davidwrote in a petitiondirected at Buckeye Police.

In aninterview with CNN, David said his son would never do something without telling them and it was unusual when they hadn’t heard from him for six hours.

“Once his vehicle was found, the way it was found, it didn’t look right, it didn’t sit right with me,” David told CNN.

Want to keep up with the latest crime coverage? Sign up forPEOPLE’s free True Crime newsletterfor breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

In late July, a skull was discovered near the site of Daniel’s Jeep. But testing ruled out the possibility it was Daniel, police stated.

David createda GoFundMe pageto assist with expenses for printing flyers, organizing search and rescue teams as well as hiring a private investigator, which he recently enacted, he said on CNN.

“I traveled from South Carolina to be in the frontline of all efforts to locate my son. Like any father, I attend on staying indefinitely until we have answers and bring Daniel home safely,” he wrote.

“I don’t have all the resources in the world, so I had to make a decision on what I need to do,” David told the station. “But I’m fighting, fighting to stay as long as I can.”

Anyone with information can reach David Robinson atpleasehelpfinddaniel.comor contact Buckeye Police at 623-349-6400.

source: people.com