Nick Herrera, president of Destiny Search, said he planned to put together a search effort Saturday to look for 55-year-old Lark Montague.
Herrera learned of Montague's disappearance from a newspaper article this week and said he hoped to coordinate the search with the Salt Lake County Sheriff's Office.
But, he said, "we are going to start the search whether they want it or not."
Searchers will be gathering at 8 a.m. Saturday at Lake Ridge Elementary School, 7400 W. 3400 South, in Magna.
Montague was last seen by a friend about 3 a.m. backing out of the driveway of her Magna home, said her husband, Dennis Montague.
Lark Montague had taken her husband's pewter-colored 2002 Chevrolet Trailblazer to a friend's house about four blocks away - without telling her husband - about 10 p.m. and returned home about 3 a.m., Dennis Montague said. A friend had followed her home and reported that she pulled into the driveway and then pulled back out, he said.
She has not contacted her family since, and there is no activity in any of the bank accounts she had access to, police said.
Salt Lake County deputies filed a missing-person report, listed the TrailBlazer on a national database for police and followed up on every lead they have gotten, said Sgt. Kris Ownby, who has supervised the investigation.
"It's peculiar and it's odd that nobody has seen her or talked to her for as long as it's been, but we don't have indication that anything suspicious happened," Ownby said.
Some family members have expressed frustration that police aren't doing enough, said Lt. Paul Jaroscak, the sheriff's spokesman, but detectives simply don't have much to go on.
"Every lead, every assumption, every theory that [family members] have come to us with, we have checked out," Jaroscak said. "At some point you just run out of leads to follow."
The lieutenant said disappearances like Montague's are bizarre but not that uncommon. So far this year the sheriff's department has received 237 missing persons reports, he said.
Detectives searched Butterfield Canyon for the SUV and even checked out a tip from the family that she may be stuffed in a closet somewhere - a tip that turned out to be phony, Jaroscak said.
Dennis Montague said he does not share the concerns of some of his seven sisters who think more could be done to find his wife.
"The police are doing as much as they can," Dennis Montague said. "You got no leads, no car, no nothing. They're treating her as a missing person, which until we find the car or her, is the only thing we can assume."
Dennis Montague said his wife was depressed and very well could have taken off. The couple cares for three grandchildren and another 3-year-old boy full time, he said.
Police said Lark Montague's prescriptions have gone unfilled, and her mother - whom Montague spoke with almost every day, relatives reported - has received no calls.
She has type II diabetes, which is manageable even without medication and not life-threatening, Dennis Montague said.
Family and friends passed out fliers and so far have received four reports of sightings of her - three in Tooele and one in West Valley City - that have not panned out, Dennis Montague said.
"My gut feeling is she's out of state somewhere," Dennis Montague said. "She has family in Texas. Hopefully she's just taking her time getting there."
Montague is described as 4 feet, 11 inches tall and 105 pounds. She was last seen driving a silver 2002 Chevrolet TrailBlazer with license plate number 215 LTE.
Anyone with information is asked to call the Salt Lake County Sheriff's Department at 801-743-7000.