CHATTANOOGA, HAMILTON COUNTY, TN (WRCB) – Nearly a month into the search for 44 year-old Gail Palmgren, investigators are looking for clues anywhere they can find them.

"It's not that we've had any particular information that the vehicle is here," said Sheriff's Department Spokesperson Janice Atkinson, "but you have to go and do this to be sure."

Each year, vehicles are pulled from a portion of the Tennessee River referred to as Suck Creek.

It sits at the foot of Signal Mountain, where Palmgren was last seen, so investigators say it was worth searching.

"We didn't see anything we could dive for," said dive team member John Scruggs, "if there was anything here we hadn't seen in the past we would dive it, but right now we're just looking at wet rock."

Crews used highly accurate side-scan sonar to navigate the 50 foot waters Tuesday morning. The search lasted two hours and covered a quarter mile stretch of the river.

Electronic images returned parts of vehicles, some 30 years old, but not Palmgren's Jeep Rubicon.

"Tires on cars, logs, rocks, we've seen even a robe off a trap we set, we can even see that line all the way up to the surface," said Scruggs, describing what the device showed.

A pair of divers followed up, to be sure the Jeep was not there. They returned to shore empty handed.

"I don't think you ever lose hope that you are going to bring someone back to their family alive and well," said Atkinson, when asked the odds Gail Palmgren is still alive.

Hamilton County and Signal Mountain authorities still refuse to comment on the investigation surrounding Palmgren's disappearance, or any potential persons of interest. They will say they are working around the clock.

"As any lead, any tip comes in, it's investigated until we can eliminate it," said Atkinson.