What we know:
He was last seen on the night of Nov. 23, 2016, pumping gas into his red Dodge SUV.
Brown is a senior honor student and class president at Canadian High School. On the night of his disappearance, Brown and two friends drove around town listening to music and talking. Friends say Brown was in a good mood and made plans for the following day. He wore jeans, tennis shoes and a black pullover sweatshirt with a small Oklahoma State University logo on the chest.
Brown returned to his car in the Canadian Middle School parking lot at 11:30 p.m. Security cameras filmed him getting gas at a nearby gas station at 11:40 p.m. before heading off towards the high school area of town at 11:51 p.m.
Brown has a strict midnight curfew, but did not return a text from his brother at 12:03 a.m. asking where he was. Phone records show Brown never read the text, nor did he read or answer any subsequent phone calls or texts from worried friends and family.
By 1:30 a.m., Brown's mother activated the local 911 emergency system and a search took place. At 6:50 a.m., cameras tracked a red Dodge SUV traveling up a remote hill on the outskirts of town. A search helicopter located the SUV at 8:45 a.m. and the Hemphill County Sheriff's Office went to investigate.
Authorities confirmed the SUV belonged to Brown. The car was unlocked with a window rolled down half way. Items missing from the car include Brown's cell phone, keys, wallet and laptop. Search dogs picked up Brown's sent in the area but eventually lost it.
Investigators believe Brown may be in danger or taken forcefully against his will. His credit cards and cell phone remain unused since his disappearance.
How you can help:
Now, authorities need help with any tips related to his location.
Chief Deputy Brent Clapp leads the investigation. If you have any information, we ask that you contact the Hemphill County Sheriffs Office at 580-276-3150. However, anybody who wishes to leave an anonymous tip can do so by calling the civil investigators Klein Investigations at 409-729-8798. Dial extension 5 to reach Caroline Gear.
Additionally, authorities urge any ranch hands and oil field workers to stay on alert and report irregularities in their work areas.
Please also take a moment to download this printable flyer and distribute it in order to spread the word. Brown is 18 years old with brown eyes and brown hair, standing about 5 feet 10 inches tall and weighing around 175 pounds.
There is a $12,500 reward for information leading to Brown's location.