A 72-year-old South Jefferson County man with undiagnosed dementia was last seen around 4 p.m. Sunday near the intersection of West Geddes Place and South Garrison Street, and deputies say he requires daily medication for diabetes that he does not have with him. Dennis Segebart is described as a white male, 6 feet tall, 135 pounds, with grey hair and a grey beard, last wearing jeans and a white shirt.
The Jefferson County Sheriff's Office is asking the public for help locating Segebart, who was driving a red or orange 2007 Pontiac Vibe sedan bearing Colorado license plate GBB5677. The two-tone description isn't unusual for the model — General Motors offered the 2007 Vibe in factory finishes like Fusion Orange Metallic and Lava Red, colors that can look similar or shift depending on the light, according to PaintScratch. Anyone who spots Segebart or his vehicle is asked to contact local law enforcement.
An Undiagnosed Condition Raises the Stakes
The sheriff's office has labeled Segebart a missing at-risk adult, a designation that reflects both his undiagnosed dementia and his need for daily diabetes medication. Missing that medication can be dangerous on its own — unmanaged blood sugar can trigger hypoglycemia, causing confusion, dizziness, or loss of consciousness, or hyperglycemia, which brings long-term metabolic complications, according to the Mayo Clinic. Paired with cognitive impairment, that risk compounds quickly.
About 60% of people living with dementia will wander from safety at least once as their condition progresses, often out of disorientation, anxiety, or an attempt to return to a familiar routine, per the Alzheimer's Association. Medical research cited by the Cleveland Clinic indicates that roughly half of missing individuals with dementia or cognitive impairment who aren't found within the first 24 hours suffer severe injury or death, underscoring why searches like this one move so urgently.
Why Formal Alert Categories Matter
Colorado's statutory Senior Citizen Alert, created under C.R.S. § 24-33.5-415.8, requires that a missing person be at least 60 years old, missing within the state, and verified by law enforcement to have an impaired mental condition alongside a credible threat to health or safety, according to the Colorado Bureau of Investigation. Because dementia diagnoses aren't always formalized, the agency also runs an Endangered Missing Alert protocol to broadcast public and vehicle information when someone faces evident safety risks without meeting the exact statutory bar for a Senior Citizen Alert. It remains unclear whether a state-level CBI alert has been triggered for Segebart's vehicle, or which direction he may have traveled from the Stony Creek-area intersection where he was last seen.
That intersection sits in a suburban pocket of unincorporated South Jefferson County near Littleton, in the 80128 zip code, an area of single-family homes built mostly in the late 1970s near arterial roads like Kipling Parkway, according to property listings reviewed on Realtor.com. Residents there can report sightings through Jeffcom 911 at 303-980-7300, the consolidated dispatch center that has handled emergency and non-emergency calls for the sheriff's office and 27 other public safety agencies since 2018.
Part of a Broader Pattern in Jefferson County
Segebart's disappearance is at least the third missing senior case in South Jefferson County that Hoodline has covered in the past month alone. A Columbine West senior found safe in early August and a woman located within two hours in a separate South Jeffco search both involved cognitive decline and vehicle travel, while another Jefferson County man in his 80s was found safe after a night search just days ago. The pattern tracks with county demographics: about 109,000 Jefferson County residents, or 18.8% of the population, were 65 or older in 2024, higher than Colorado's statewide senior share of 16.5%, per U.S. Census Bureau data cited in prior Hoodline reporting.
The Jefferson County Sheriff's Office also runs a Victim Services Unit offering 24/7 crisis intervention advocates who support families through traumatic events, including elder welfare emergencies and missing person cases. It is not yet known when Segebart last took his diabetes medication or which direction he was heading when he was last seen. Anyone with information on his whereabouts is urged to contact local law enforcement immediately.
