UPDATE October 21, 2018:

Ricky Dale Howard, a person of interest in the spring 2015 disappearance of Caleb Diehl, was indicted last week on 15 new felony counts that include indecency with a child connected with Diehl and 12 counts of possession of child pornography with unknown victims.

The 57-year-old Nocona man has been serving prison time in the Hamilton Unit of the state prison system in Bryan since June 2016 when he pled guilty to possession of firearms by a felon. He received five years on the 11 counts. As a convicted felon for federal bank fraud it is illegal for him to possess firearms.

The Times Record News in Wichita Falls, Texas reports Howard was up for parole consideration earlier this summer, but it was denied in July after he was indicted in April on two counts of indecency with a child sexual contact and 34 counts of child pornography.

MORE: Person of interest in disappearance of Caleb Diehl charged with 15 new felony counts - Times Record News

May 16, 2016:

Just two weeks after his 18th birthday, Texan Caleb Diehl borrowed a family friend's truck on March 30, 2015. He was never seen again.

Nobody has seen any sign of Caleb since the day he disappeared from his mother's house in Nocona, Texas, about 100 miles northwest of Dallas, with a population of just over 3,000 people. It's a small town with some heavy baggage.

Caleb Diehl is the youngest of the family, with three sisters and a brother.

Caleb's sister Courtney is the last one who saw him alive on a Monday evening when he headed out the door. And now nobody has any idea where he's gone.

"He said he was going to visit a friend which, his friend wasn't even in town we found out later," said Courtney. "That was the last time I saw him."

According to police, the friend in question later said that he and Caleb never had any plans to meet.

Caleb was driving a Chevrolet pickup truck borrowed from Ricky Howard, a family man with a wife and three kids, and a close friend of Caleb's family as well.

Ricky Howard is a successful and popular businessman in town, but has a checkered past. A former bank president, he was convicted and served time on bank fraud charges in 2007. But he still keeps his friends close.

"He was a good friend. He was the kind of friend, if you needed something, he was the first one to be there and help you," said Chad Diehl, Caleb's father. "He was a kind, enjoyable guy to be around."

Caleb works odd jobs for Ricky, who has investments in farming, cattle and oil wells, and owns several properties in the area. In fact, police say that the last known person that Caleb contacted before his disappearance was Ricky Howard.

"Ricky Howard told us that Caleb told him he was wanting to borrow the truck to go to Oklahoma, where he'd met a girl and work for her uncle," said Nocona Police Chief Kent Holcomb. "Nobody else knew anything about it. That's just what Ricky told us."

And when nobody in the family sees or hears from Caleb for two days, one of the first people they contact is Ricky Howard. He tells them the same story about Caleb running away to Oklahoma.

Two days after Caleb disappears, his mother Tami Diehl filed a missing-persons report with the police.

As she heads out to file the report, the borrowed pickup truck suddenly shows up the same day -- but without Caleb -- right in the middle of Ricky Howard's locked garage.

And police say the truck in Ricky's garage raises some important questions that are still unanswered to this day.

"There was three hundred dollar bills zip-tied to the steering wheel," said Holcomb. "The key to the shop, which is normally above the walk-in door to get into the shop, was in the seat of the pickup. The shop was locked up, only other person who had access to the shop was Ricky Howard, so it was kind of suspicious.

"[Ricky Howard] was normal. He was not excited. He just wanted to report it," said Holcomb.

Nobody has an explanation for the money zip-tied to the steering wheel. But Ricky Howard fully co-operated, giving cops permission to search his property.

Ricky was charged with illegal possession of firearms after guns were found in his safe.

"We didn't find any computers that were up and running," said Holcomb. "We did find some that had been destroyed and burnt. They were burned."

According to police, Ricky's place is a hotbed of destroyed technology.

"[Caleb's] cellphone was never recovered by us," said Holcomb. "After interviewing Ricky Howard he stated that he found a cellphone smashed in the shop when he was taking the garbage out, threw it in the garbage, by the time the truck was found the garbage had been picked up, so we had no evidence if that was Caleb's phone."

Police comb the surrounding countryside with dogs searching for any sign of Caleb.

"It wasn't until a couple weeks later that all the pieces of the puzzle that had the Texas Rangers and the FBI persuaded that Ricky was involved with Caleb, and that this was their persuasion," said Chad Diehl. "I couldn't ignore these people in their line of business that they're in."

There is no move to charge Ricky with any foul play in Caleb's disappearance, and the Texas Rangers and the FBI have not responded to Crime Watch Daily requests for comment.

Chad says he cannot rest until he clears the air with Ricky Howard.

Unable to remain silent, Chad heads to Ricky Howard's house and confronts him man to man with his suspicions. It is a dramatic and frightening encounter.

"I said 'Well Ricky, I want you to know, and I want you to hear it so it's not a rumor, that I believe with every fiber of my heart, my soul and my mind that you murdered my son,'" said Chad. "No expression of sadness, no out-showing of anger. He said 'Well, I'm sorry that you believe that.' I said 'Well, that is what I believe and I gotta go.' And I got up and I turned and walked out. I didn't have to get into the reasons why I believe. He knew why. It was the most intense moment of my life, for sure."

Chad has his theories and police have their suspicions.

"I would say Ricky Howard is a person of high interest. That's what I'd say," said Chief Holcomb.

To be clear: Ricky Howard has not been charged with any involvement in the disappearance of Caleb Diehl. As his attorney Bob Estrada will gladly tell you.

But in the course of the investigation into Caleb's disappearance, other shocking developments now come to light.

It happens when police interview a man who once worked for Ricky Howard. When he was a teenager, he says, Ricky Howard molested him.

"Right, during the interview process he goes on and states that," said Holcomb. "It was a long time ago."

How many boys subsequently have come forward?

"At this time, I want to say five or six. Several of them are outside the statute of limitations, as of right now I believe two or three," said Holcomb.

The Diehl family says they don't know if Caleb was victimized by Ricky Howard.

After posting a bond of a half-million dollars, Ricky Howard is preparing to appear in court on multiple charges: illegal possession of firearms and four counts of aggravated sexual assault of a child.

"The pleas for the aggravated sexual assault is not guilty," said Howard's defense attorney Bob Estrada. "The plea to the gun charges is something we're going to resolve before the court."

One of the people they interviewed who worked for Ricky Howard, he came clean and said that Ricky Howard molested him 20 years ago, 500 times over a four-year period.

"Think about that," said Howard's defense attorney Bob Estrada. "Five-hundred times over a four-year period, and he says nothing. He was able to talk."

But he said Ricky Howard kept a rifle in his truck, and that he was scared.

"This is a rural area," said Estrada. "People keep rifles in their truck all over the place."

Estrada does have at least one theory about what really happened to Caleb.

"There's other documented stories of people who have walked off and started a new life," said Estrada. "There are other people who simply start a new life somewhere else. And at 19 he'd be able to do it."

Caleb Diehl has blond hair and blue eyes and stands 6 feet 2 inches tall, weighing 145 pounds.

UPDATE June 29, 2016: Ricky Howard made a plea deal: Guilty to three counts of unlawful possession of a firearm. He was sentenced to five years in prison and could be paroled as early as next year. But his attorney, Bob Estrada, says he's going to fight the sexual assault charge.