Fifty-three-year-old New Mexico woman Melissa Casias has been missing since Thursday, June 26, 2025.
Her family doesn’t understand why.
“I can’t grasp it,” her husband, Mark Casias, told Dateline. “I don’t know. I can’t figure it out.”
Mark says the last time he saw his wife was around 6:15 that morning when she dropped him off at Los Alamos National Laboratory (LANL) — a research lab in Los Alamos, New Mexico, where he and Melissa both work. “She took me, dropped me off, and I told her I needed the car by around 11,” he said. “She said she’d have it back by about 11 o’clock, like she usually does.”
Mark says Melissa told him she was going to another location within LANL to complete a task for work and drove away. “That was pretty much the last I spoke to her that day,” he said.
Mark told Dateline that there was “nothing out of the ordinary” about his interaction with his wife that morning — a moment he’s replayed in his head for weeks.
According to Mark, and unbeknownst to him, Melissa then returned to the home they shared with their daughter Sierra more than an hour away in Ranchos de Taos. Dateline spoke with Sierra, who said she woke up around 7:30 that morning and heard her mother come into the house about 15 minutes later.
“I was like, ‘What are you doing home?’” Sierra remembered. “She said that she had forgotten her badge.”
Having no reason to question her mother, Sierra accepted that Melissa had simply forgotten the badge she needed to enter LANL. In retrospect, it’s one of the most confusing details for Melissa’s family as they try to piece together what happened that day. “You’ve got to show your badge to get in — and it’s always the driver,” Mark told Dateline. “She showed her badge.”
Melissa told Sierra that she had decided to “either work from home or call out for the day” after arriving home that morning. “Nothing was unusual. Her behavior wasn’t different. Nothing that caught me off guard,” Sierra said. “Right when I was leaving, I always hug her bye, say ‘I love you,’ all of that. We did that — that’s normal.”
Sierra says she left for work shortly after that interaction.
Around 12:30 p.m., Melissa picked up a Subway sandwich for Sierra’s lunch and dropped it off at the café where Sierra works in Taos Plaza, a business center in Taos. Sierra says the two spoke briefly and then she handed her mother a check to drop off at the bank for her and her mother left. In an email on behalf of investigators, New Mexico State Police PIO Sergeant Ricardo Breceda confirmed to Dateline that the two spoke from 12:50 to 12:57.
“She may have been a little more quiet, but still — nothing that caught me off guard. Because if she’s running errands, she’ll just run in and out because I’m going to see her later. So I gave her my check. She dropped off my food,” Sierra said. “She said, ‘Love you,’ and she walked out. Again, nothing weird, nothing — her demeanor wasn’t out of the ordinary.”
Sierra hasn’t seen her mother since that moment.
When 11 a.m. passed and his wife hadn’t returned with the car, Mark says he figured Melissa had gotten busy at work. Until he got a call from her boss in the afternoon. “She says, ‘Is Melissa OK?’ And I’m like, ‘Yeah, she should be at work,’” he recalled. “And that’s when she told me, ‘Well, she isn’t at work.’”
Mark says he tried to reach Melissa after hearing from her boss, but was unable to do so.
Sierra says she got a text from her father around 1:30 p.m.
“He was seeing if I was getting in contact with my mom. And I said — I told him, ‘Yeah.’ So he had asked me, um, ‘Can you text her and ask her if, um, I need a ride or if she’s going to come pick me up?’” Sierra remembered. “So I texted her. I was like — I just texted the screenshot to her. And she had read it. And so I assumed that she was just gonna call him, or whatever that they do. And I didn’t think — I paid no mind to it.”
The last known sighting of Meliss Casias was approximately 45 minutes later.
“On June 26, 2025, around 2:18 PM, [a] family acquaintance observed Melissa walking eastbound on NM518 from the Talpa, New Mexico, area towards Pot Creek,” Sgt. Breceda wrote Dateline.
The sighting — which was about three miles from the Casias home — was also captured on security video from a local business, Kit Carson Electric Company. “She is observed walking Eastbound on NM 518 and wearing the clothing she was last reported wearing in the Taos Plaza (light color shirt, jeans, light tennis shoes),” Breceda wrote. “It is Difficult to tell if she appears distressed.”
Melissa’s family believes she may have gotten inside a vehicle shortly after she was seen on the video, which NMSP investigators describe as “a possibility that is being investigated,” according to Breceda.
Around 2 p.m., while in the middle of a rush at work, she began getting calls from her father. “I could not get to the phone for another, like, 20 minutes. So it was 2:30 when I finally got to the phone,” she said. “I saw one of his voicemails. He sounded frantic, or just — not frantic, but he sounded worried.”
Mark told Sierra he still hadn’t heard from Melissa.
Sierra then reached out to her mother again. “I texted her, I was like, ‘Hey, Dad’s freaking out. Like, why aren’t you — haven’t you answered?’” she said. “My text — it didn’t deliver.”
Worried, Sierra left work around 3:30 to go home. “The door was locked; the car was home. I saw immediately that the keys and her work phone were on our kitchen table,” she said. “I just went and searched the house just really quickly.” While looking around the home, Sierra went into her mother’s office. “That’s where I found her phone, her purse, her wallet — all of her personal items,” she said. “I had clicked on the phone and it showed, like, a factory reset. It had been wiped, or whatever. And that’s when I got really, really worried.”
Sierra also found the check she had given her mother hours earlier to take to the bank.
Sergeant Breceda confirmed to Dateline that “all belongings, including Melissa’s purse and factory reset phones, were found inside Melissa’s home.”
Mark was dropped off at home by a coworker shortly after Sierra got there. He reported Melissa missing at 5 p.m., according to Breceda.
News about Melissa’s disappearance quickly spread to the rest of the family. Melissa’s niece, Jazmin McMillen, told Dateline that her family made the two and a half hour drive from their home in Albuquerque to Ranchos de Taos as soon as they heard the news. “We were all kind of just gathered out in the parking lot and racking our brains on what to do,” Jazmin said. “We immediately went into, like, action mode.”
On Saturday, June 28, Jazmin helped organize a search for Melissa using a hunting app in which hunters can mark the areas they’ve covered. “We created a map of the probable area where she might be based off of where she was last seen,” she said. “And then we had probably 125 volunteers from the community come out.”
Melissa is an avid archer. According to her niece, members of the archery community banded together to participate in the searches — a testament to the kind of person she is, according to her niece. “The community has really come together, and it has been very supportive,” Jazmin said. “People have shown up searching for her from El Paso, Texas, from Clovis, from Colorado — archery community is really huge, and she’s a big part of it.”
Four days after Melissa went missing, “search dog[s] from Taos Search and Rescue searched NM 518 from the intersection of NM 68 / NM 518 Eastbound towards the intersection of NM 518 / FR 437,” Breceda told Dateline.
He also wrote that several agencies also searched an area of about 100 acres on July 2. Three days later, “an estimated 283 Acres of Carson National Forest, including river streams and both sides of NM 518” were also searched.
Despite the efforts of her family and the NMSP, Melissa has not been located.
For the past few weeks, Mark and Sierra have gone through Melissa’s documents and discovered that she may have been experiencing pressures that they didn’t know about. “Through our own research — she was going through a huge, huge, huge amount of stress,” Sierra told Dateline. “There is a lot crumbling down on her that we didn’t know about.”
Still, it doesn’t make sense to them why Melissa — who gave no signs of wanting to leave home — would disappear. “There’s no way that she would just do this without telling me,” Sierra said. “Why wouldn’t she leave me a note? Why wouldn’t she text me? Why wouldn’t she tell me? Even just, like, a hint.”
The family also had a lake trip scheduled for June 27 — the day after Melissa went missing. “She knew I was super excited about it,” Sierra said. “So that made her excited.”
Jazmin McMillen says her mother and her aunt also had plans to take care of their mother, who was getting knee replacement surgery a few days later. Melissa “was planning on taking the day off of work so that she could be there at the hospital,” she said. “My mom and Melissa were talking about how they were going to divide up care to take care of my grandma as she recovered.”
Melissa’s husband says he is distraught at the thought his wife may have been secretly in pain. “I feel so bad. I didn’t recognize this,” he said. “She hides everything well, and, you know, she would smile. I mean, every day she smiles.”
Dateline asked NMSP if they believe that Melissa disappeared of her own volition. “From the facts we have gathered, it appears this may be the case,” Sgt. Breceda responded on behalf of investigators. He also said foul play has not been ruled out and that the department is “looking into every angle of this investigation.”
“We have been conducting a follow-up on all the information received since the beginning of this investigation. It has been difficult filtering through rumors and identifying factual information,” Breceda wrote. “Nobody has been cleared at this point.”
Melissa’s family is concerned for her safety. “Our biggest thing is her mental state,” Sierra said. “We have no idea what’s going on.” Sierra describes her mother lovingly and just wants her to come home. “She just has this very good aura. She’s the emblem of a good person.”
Mark shared a similar sentiment for his wife of 20 years. “She’s the most wonderful person. I — she’s always smiling,” he said. “She doesn’t get angry. She’s just, like, a lovable person.”
He wanted to share a message directly with Melissa in the event that she is reading this article: “It is OK. We can solve any problem that, you know, that — that might be there. We can solve it all. Come back,” he pleaded. “Just communicate with us, and I’ll go get you wherever you’re at. I don’t care if you’re, you know, across the world. I’ll go get you — and this, too, shall pass.”
Melissa is 5’4” and approximately 115 lbs. She was last seen wearing a light-colored shirt, jeans, and light-colored tennis shoes. She has brown hair and eyes. She has multiple tattoos including a dragon on her right ankle, dream catcher on her left shoulder, and a bow and arrow on her left arm. Her family is offering a $5,000 reward for information that leads to her safe return.
Anyone with information about Melissa’s disappearance is asked to call New Mexico State Police Dispatch at 505-425-6771.
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