New London -- Paige Knobel says her father, Tom Doolan, would never miss celebrating his grandson's birthday or Christmas with his family.

But he was nowhere to be found for either celebration this year.

The 59-year-old city resident has been missing since Dec. 6 when he sent his only daughter a text at 10 a.m. that read "I love you more than anything in the world, that's why I want to get some help."

Since then, no one in his family, or at the sober house at 57 Berkeley Ave. where he has lived since the summer, has seen or heard from him.

Doolan, who has a history of drug addiction, mental illness and suicidal tendencies, has not used either his Social Security of EBT card - his two sources of funds - since Dec. 5. His phone has gone straight to voicemail for every call.

Knobel last saw her dad on Dec. 1 when the two went to Walmart with her young sons to shop for Christmas gifts. Doolan picked out a Leapfrog dinosaur for Logan, 2, and two Lego sets for Patrick, who turned 6 on Dec. 20.

She last heard from him five days later when he called and texted in what she described as a "manic state."

"He wasn't making any sense," she said. "He was not like himself and was saying delusional things."

Knobel said her dad has struggled with drug addition her entire life, but has been sober for 18 months and has lived in a sober house for over a year. He has been diagnosed with bipolar disorder with manic episodes and has previously attempted suicide multiple times, she said.

But even in manic states and when using drugs, she said, he never missed a birthday.

"His pattern has never changed and this is just out of character for him," she said.

Knobel said her dad was also acting differently on Thanksgiving, which he spent at her Colchester home. Doolan was a lifelong Colchester resident who moved to New London for a fresh start after getting sober in time for Knobel's wedding last September.

Knobel said she wasn't too worried when her father's phone went to voicemail for a few weeks this month, she figured he'd checked himself into a hospital, she said. But when her son's birthday approached - the same day her husband, Mark Knobel, was returning home from a two-month deployment in the Navy - and her dad still hadn't called, she began to panic.

On Dec. 19, Knobel spoke with Doolan's visiting nurse who said she had not seen him in weeks and hadn't received any notification that he was in a hospital or treatment center. Knobel then called New London police and requested a wellness check.

She soon spoke to the manager of his sober house, who told her that Doolan hadn't been home in two weeks, but that all his stuff had been left at the house. Another worker at the sober house told Knobel her dad had become difficult to live with in the past month and had gotten worse since the Thanksgiving holiday.

On Dec. 23, she reported her dad missing to police.

Knobel said she has called local hospitals and treatment facilities where she thought her dad might turn for help, but has found no leads. She said she has no idea where he might be.

"I've called every possible place that he would go to where he would get some help, he's not anywhere," she said. "Everyone who was close to him has this horrible feeling that he's no longer with us."

Knobel's mother, Suzanne Cordova, has been taking to social media to locate Doolan.

"We've exhausted every possibility with numerous calls all over the state," she wrote in a post on Facebook on Christmas Day. "Regardless of his past this is VERY out of character for Tom. He's never went this long not contacting his daughter. Ever. We need help."

Knobel said that her dad liked to walk to stores near his home in New London, and that she'd heard he would walk down to the water to watch the ferries come and go.

If he wasn't on foot, her father rode a black bicycle, she said. He has a black coat and might be wearing blue jeans or tan or black work boots. A few months ago she bought him a black backpack that he was likely carrying, she said.

"If anybody sees him or anything, yell out his name and if he replies then try to get him to talk to somebody, then call police or call me," said Knobel. She asked that anyone with information call her at (860) 639-1356.