The father of a missing 13-year-old Wisconsin boy said he believes his son drove away from home in a family van — potentially at the request or coercion of another person.

William Yoblonski reported his son, James Yoblonski, missing on June 12 to the Sauk County authorities, saying the 13-year-old fled their Reedsburg home in the family van overnight, possibly with William's handgun.

"It's not like him to do anything like this," Yoblonski, a single father with four children, told Fox News Digital. "I mean, he's never driven my vehicle on the streets or anything. He's moved my van around my shop a couple times. That was it."

Video footage caught James walking out of his home around midnight on June 12 and walking across the street to the family van. He sat inside the van for about an hour before taking off, his dad explained.

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James Yoblonski inset over Devils Lake rock formation Devils Doorway

A photo of missing 13-year-old James Yoblonski provided by the Sauk County Sheriff's Office inset over the Devils Doorway rock formation at Devils Lake State Park in Wisconsin. (iStock, Sauk County Sheriff's Office)

Investigators discovered searches on James' electronic devices "about being a minor on an airplane and crossing state lines," his dad said.

James also took his father's cell phone when he left home, which pinged on the western edge of Devil's Lake State Park on June 12, according to the Sauk County Sheriff's Office. 

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Detectives found a makeshift campsite inside the park that they believe the boy used, but William Yoblonski doesn't think his son spent the night at the camp because search dogs did not pick up his scent in the area.

The entrance of Devil's Lake State Park

James Yoblonski also took his father's cell phone when he left home, which pinged on the western edge of Devil's Lake State Park on June 12, according to the Sauk County Sheriff's Office.  (Google Maps)

"I think he left with somebody. I think he sat there and waited for a horn to honk and came out and got in the car with somebody," William explained.

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William thinks James met someone online or in person who may have coerced and possibly instructed him on how to leave home. In a Snapchat video posted from William's phone, James apparently said something along the lines of, "'I'm sorry. I don't think I'll be back for school. I don't want to hurt anybody, but I might,'" William said.

He added that the "strange thing" about the video was the angle at which James recorded it in the family van he drove off in during the early morning hours of June 12. 

"My cup holders in my van will not hold that cell phone," William said. "Somebody else was with him holding their cell phone" while recording the video of James, he added.

Authorities eventually found the Yoblonskis' family van unattended in Sumpter, Wisconsin — about a 30-minute drive southeast of Reedsburg.

William said he knows he is a suspect in his son's disappearance, but he recently passed a polygraph test from authorities that he said proves otherwise. He added that he is "very upset" with the sheriff's office for a lack of answers. William is also offering a $100,000 reward for information leading to his son's whereabouts.

"I just want my son back. That's why I put up a $10,000 reward. If I could afford to go more than that … but I just don't have that kind of money. Like I said, I'm a single father," he said.

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The FBI has since joined the search for the missing youth. 

Anyone with information on James' whereabouts is asked to call the Sauk County Sheriff's Office at 608-355-4495.

Fox News' Michael Ruiz contributed to this report.