David Waggoner’s October 1971 disappearance in Pasadena, Texas

"I miss him so much. I've missed him all this time," Diana Waggoner Shurbet told Dateline. "And I have prayed to God every day since he's been gone."

Diana's younger brother, David Waggoner, has been missing since October 1971.

And even though 53 years have passed, Diana refuses to give up looking for answers.

Diana and David grew up with their two older siblings in Rockport, Texas. "We did everything together here in Rockport," Diana said. "Growing up, we were always at the beach, playing baseball. You know, just doing things together."

David graduated from high school in 1966 and joined the Marine Corps soon after. "He would come home on leave," Diana said. "David got out of the Marine Corps, I think it was 1970."

By then, Diana was married and had moved out. Their parents had left Rockport and were living about three hours away in Pasadena, Texas — just outside of Houston. When David got out of the Marine Corps, he found work in Pasadena. "He lived in an apartment close to my mom and dad," Diana said. "At the time, he didn't have a phone." David lived alone in that apartment.

It is unclear exactly when the 23-year-old was last seen or heard from, but in October 1971, alarm bells began to go off for the Waggoners. "My mom hadn't seen him in a couple weeks. And she went over to the apartment complex," Diana said. "And the manager said she hadn't seen David for about a week." Diana thinks this exchange occurred right around October 9.

The manager agreed to open David's apartment for their mother. "When she went into the apartment, it was just like he was coming back," Diana said, explaining that nothing really looked out of place.

The family did identify two things that were missing. "He had a motorcycle. It was gone," Diana said. "We knew he had a gun." The gun was not in the apartment. Diana thought maybe David had just gone to do some target practice. "He would go target practicing and everything," Diana said. "We didn't think much of it."

"He loved riding his motorcycle," Diana said, despite having previously had some serious injuries. "He had two skull fractures and was in Corpus Hospital for some time, and then he's had other accidents. He had broken his collarbone."

Diana says, at first, the family thought maybe David just wanted to get away. "He had quit his job about a week or two before that happened - before he disappeared," she said.

"The longer it went on, my husband Rick said, 'Diana, there's no way your brother would have just left and not gotten in touch with you,'" Diana recalled. "So my mother went to the police department and reported him missing. And that was the Pasadena Police Department."

Dateline spoke with Detective C.A. MacGregor of the Pasadena Police Department. He works in the Violent Crimes Unit and also heads up the Cold Case Unit. "Back in 1971 is when the report was originally taken, that, you know, he left home and hadn't been seen from or heard from," he said. "When his family inquired later on, in 1995, they couldn't find the original report. So they created a case number in 1995 and then kind of picked up the case from there."

MacGregor told Dateline he has "reached out to various agencies" to "obtain as much information" as he could on the case, but there wasn't much information to gather. "It wasn't so much like we had a crime scene, like a homicide, to have processed and then, you know, had evidence," Det. MacGregor said. "This is a missing persons [case] and the only thing that was recovered was his motorcycle and helmet up alongside the highway."

David's motorcycle was recovered north of Pasadena along Highway 59 about two weeks after he was reported missing. "It runs from Mexico all the way up to Canada," Det. MacGregor said. "Where his motorcycle was found, it's maybe an hour from [Pasadena]."

"It's a major highway, but it wasn't, like, off in the woods on trails or anything. It was literally just on the side of the highway, key in the ignition and the helmet resting on the bike," MacGregor said. "It was processed by the San Jacinto County back in 1971." The San Jacinto County Sheriff's Office handled the search for David in that area. "From reading the report, they conducted a canvass in the event that he wandered off into the woods," the detective explained. "The initial search, nothing was found."

Dateline reached out to the San Jacinto County Sheriff's Office to ask about their initial search efforts in the case but has not yet heard back.

"There was a deceased person found at some later point in the forested area off that highway," Det. MacGregor told Dateline. "But it turned out not to be Waggoner."

Diana also went up to the area where her brother's motorcycle was found. "You could search for days. I mean, it was so thick in there," she said. Nothing else was ever found that was connected to David.

Diana told Dateline she has some theories about what might have happened to her brother, but none of them has yet proven to be true. There is one thing Diana knows for certain. "I would not ever believe my brother David committed suicide," she said.

According to Detective MacGregor, the department does not have much to go on. "There's not enough information to reclassify, or you know, articulate that there was, you know, foul play involved," he said. "Nothing's going on in his life that would, you know, make us believe, like, 'Oh, he was involved in something,' you know, that would cause his demise or to, you know, be subject to foul play. That's kind of the unfortunate part - is just the lack of information."

Even though it's been half a century since David disappeared, MacGregor says his case remains open. "It comes down to what evidence we come across," he said. "Tips are - are definitely wanted, but it's what we can do with that information given the time frame that's passed to which you can corroborate."

MacGregor says it's difficult to confirm information that comes up 50 years after the fact. "A lot of information is perishable," he said. "The only thing that was found was his motorcycle. And that's the only thing we have to go on. And again, that was recovered back in 1971." That presents a challenge today. "The way they processed crime scenes and how they handled evidence, um –- way different than how we do it now," he explained.

With most of the family now gone, Diana has dedicated herself to getting answers for her younger brother. "I have a notebook, and I've been, of course, over the years making notes. I've contacted - I couldn't tell you how many talk shows," she said. David's story was told on The Vanished podcast in 2016.

Diana reached out to Dateline. "After I got your email, it was kind of like, I didn't even know what to think. I didn't want to get my hopes up. And I started crying and I - and I said, 'Thank you God,'" she said. "Every time someone finds out about David and wants to do something, I know God is - God is responsible for that."

If he were still alive today, David would be turning 77 in November. "He was 23, almost 24 when he disappeared," Diana told Dateline. "I wasn't that much older than him. But I was very protective of him."

David was about 5'9" or 5'10" and weighed between 160-170 lbs. when he went missing.

He had dark brown hair, brown eyes and wore glasses. Detective MacGregor says his department has David's dental records on file and has collected DNA from Diana, "to help identify him, in the event he was found."

"I probably in my heart know that he's not alive," Diana told Dateline, but "there's always that little bit of hope."

If you have any information about the disappearance of David Waggoner, please contact the Pasadena Police Department at 713-477-1221. You can also contact Det. MacGregor at 713-475-7891.