CHATTANOOGA (WRCB) - Nearly three months since she was last seen, the big question remains: Where is Gail Palmgren?

The Signal Mountain mom disappeared April 30, 2011, and by all accounts, left no trace of where she was going.

Hamilton County detectives joined Signal Mountain Police two weeks later to help with a missing person's case and today Sheriff Jim Hammond says it remains a missing person's case.

"There's nothing at this point to indicate that anything nefarious has occurred," Hammond told Channel 3.

The sheriff did say that it's extremely unusual for a mom to go this long without making contact with her children.

"From a mother's standpoint, they would say, 'I could tell you one thing, if she loved her children, she's dead, cause she'd be trying to get to 'em,' but we have to deal with the reality and we just don't know what that is right now," Sheriff Hammond said.

There's been no verified sighting of Gail Palmgren since a neighbor reportedly saw her leaving her house on Ridgerock Drive in the St. Ives neighborhood on Signal Mountain.

No credit card activity. No calls from her phone.

Earlier this month, Gail Palmgren's siblings pushed Hamilton County District Attorney Bill Cox to write a letter asking Chattanooga agents with the Tennessee Bureau of Investigation to review detectives' work on the case to date.

Now, the Federal Bureau of Investigation is becoming involved in the case.

Special Agents spent two hours Monday morning interviewing Gail Palmgren's friend, Arlene Durham.

She says she told the feds that she believes Matt Palmgren knows more about his wife's disappearance than he's telling.

"If we can find the Jeep, we can find her. And I think he knows what happened to the Jeep and what happened to her, where she's located," Durham told Channel 3 Eyewitness News. "You don't hide behind a criminal defense attorney, your girlfriend doesn't hide behind a criminal defense attorney, your mom doesn't hide behind a criminal defense attorney if you have nothing to hide."

Sheriff Hammond says if Gail did not disappear by her own choice, it's likely that someone has information that can help investigators learn what happened to her. Especially since Palmgren's 2010 Ruby Red Jeep Rubicon has also disappeared.

"It would be very difficult for you to plan to get rid of someone and a Jeep and not leave some piece of evidence that someone saw," Hammond explained.

That means it's critical for anyone who has information about Gail Palmgren, no matter how insignificant it may seem, to pass along that information to detectives.

"There's enough physical evidence out there that we'd like to take a look at, that tells us that hopefully there's someone out there who can provide a piece of information that we need," the sheriff added.

If you have any information about what happened to Gail Palmgren or where she is now, please call Hamilton County detectives at 209-7000.