The letters detail Cook's life and things she wishes they could have shared together. This year Cook, who was 5 when her mother Bobbi Ann Campbell vanished on Dec. 27, 1994, wrote about her wedding.
"Every year that goes by is just another year that people put it behind them," said Cook, 20. "It is just harder to keep the hope."
And every time there is news that a mother is missing, the heartache intensifies. This time, it is Susan Powell's story that has riveted Cook. Powell, mother of sons ages 4 and 2, was reported missing from her West Valley City home on Dec. 7.
"I just hurt for those little kids," Cook said. "I pray that they don't have to grow up with no answers like I did."
That pain is shared by families throughout Utah who have had loved ones disappear with few clues to what happened to them or why. The Utah Missing Persons Clearinghouse, the state's official database, now features Powell in addition to 55 others.
Of those, 42 are adults ages 19 or older. A majority -- 26 -- of those adults are men. A number of cases on the list involve suspicious circumstances that suggest foul play. Names are added only with permission of family or law enforcement.
It's not a complete list, acknowledges Gina McNeil. Across Utah, missing persons reports pour in daily. In Salt Lake County, for instance, the sheriff's office had received 157 reports in 2009 as of Dec. 30 -- a count that doesn't include runaway children.
Spokesman Don Hutson said most cases are resolved quickly after a person returns or is located and relays they left by choice. Those that make the state database stay there until a person is found or a body recovered. Kiplyn Davis of Spanish Fork is listed, for example, though authorities and her family believe she was killed after she disappeared in 1995.
The oldest case dates to the 1970s: Jennifer Klein, 3, disappeared in May 1974 while camping with her family in Moab near a river. Klein's entry notes her family doesn't recall anyone at the campground being interviewed or vehicles searched.
Since then, investigative techniques, technology and media have vastly altered efforts to locate missing persons. Information about Susan Powell, for instance, spread worldwide via the Internet within days of her disappearance.
Advances in DNA matching have allowed investigators to rework old cases, as has age progression imaging.
Bobbi Ann Campbell's case is one that received new attention earlier this year after the group "Project Jason" released a photograph that showed how she might have aged.
Campbell was 24 when left her daughter with a friend while she picked up a paycheck from SOS Staffing Services in Salt Lake City, went to the bank and then the grocery store. She never picked up her check. Investigators believe Campbell, who had struggled with drugs, was spotted about six months later at a park.
That fall, Campbell's vehicle was found abandoned in front of a home near the Jordan River. Inside the vehicle, family found her makeup, purse, clothes and even Christmas presents from the previous year.
Cook, who was raised by her great-grandparents, said they did everything they could to find her at the time. Several years ago, Cook took up the charge and contacted every missing persons Web site she could find to spread word about her mother. Cook also submitted a DNA sample that could be compared to any unidentified bodies found.
"I pass out fliers once every so often," Cook said. "I did it this summer at Liberty Park because that is where we would hang out all the time when I was little. That is all I can do.
"I hope that something happened and she is just confused and scared to come home," Cook said. "I honestly don't think she could have left me because of how close we were."
Occasionally, a missing adult resurfaces -- or Sarah Jensen of Orem.
Jensen left home on May 25 to camp for a few days in southern Utah. Jensen's family reported the 31-year-old mother missing a week later when she failed to return home. As a search began, Jensen's parents said their daughter would "never, never" have left her 5-year-old son for so long, said Hutson.
Three weeks later -- as Jensen's family prepared to hold a candlelight vigil -- Jensen was pulled over during a routine traffic stop in New Mexico. Jensen told police she had been staying with friends and had not wanted to be contacted for a while, though she did return to Utah at that point.
In such cases, there is little police can do, Hutson said.
"It is not a crime to walk away from your marriage, to walk away from your job or leave your family behind," he said.
Sometimes, there are sad discoveries.
In November, 51-year-old Katherine S. Doutre of Hooper disappeared after dropping off her son at Roy High School. Doutre did not take her cell phone, wallet, car or keys and was distraught; she had taken off in the past for hours but always returned. When a day passed, family contacted police. Searches turned up nothing, though there were several credible sightings of Doutre.
A month later, Doutre's body was found in a previously searched field near West Haven. Police determined she had died of exposure, probably not long after she disappeared.
Often, though, a missing person is never found.
Family are left with unanswered questions and, at some point, the sad tasks of cleaning out homes, disposing of possessions, ending marriages, taking care of estates and other legal matters.
Lee "Bill" Frost never got over the disappearance of his daughter Debra, who was 17 when she vanished in 1984. She was last seen around 10 p.m. in downtown Salt Lake City, at the Mountain Bell Plaza.
Frost, a taxi driver, died in 2005. His obituary noted that Debra's disappearance "sadly altered Bill's life forever." Later that year when his estate was settled, a court ordered that Debra's shared be given to her siblings.
The daughters of Janis Stavros, missing since Jan. 3, 2001, had their mother declared legally dead last year, said Stavros' ex-husband Mike.
Mike Stavros and his ex-wife, her boyfriend and daughter Meghan Laudie had a dinner together on Jan. 2.
He said that "at some point things got weird" and Stavros and her boyfriend left about 10 p.m. to return to her Millcreek home.
The next day, Stavros' daughter could not reach her and sounded the alarm. Her boyfriend told police Stavros was home when he left for work earlier that morning. Police found her vehicle, purse and cell phone in her home, but Stavros was gone and searches turned up nothing.
"There is absolutely nothing new," Mike Stavros said. "I wish there was.
"It's impossible to not endlessly wonder what happened," said Stavros, who now is remarried. "We know she's gone, that is all we know. When you get no answers, there is an empty feeling that goes with that."
Hutson said Stavros' case haunts him. He was a sergeant when Stavros disappeared and worked on the investigation.
"It was literally as if she was wiped off the face of the earth," he said. "Nothing was taken. It wasn't like she was in a bad marriage. There were no signs of a struggle in the home and all her belongings were left at home."
Dennis Montague, whose wife Lark Mosher Montague disappeared in September 2007, said that search also "hit a dead-end street." She drove off in the early morning and hasn't been seen or heard from since.
"We can't find the car or anything," he said. "We can't find nothing."
Meantime, her family has marked time and family events without her, including the death of her youngest son last year. His obituary listed his mother, but did not mention that she is missing.
Hutson said it becomes more difficult to solve cases as times passes without new information or evidence.
The one thing that doesn't change?
"There are families who would appreciate having some answers," he said.