Ashley Martinez and her younger brother spent the Fourth of July weekend in 2004 at Krug Park, St. Joseph, Missouri.Tammy Mack, their mother, gave Ashley, 15, the responsibility of driving them to school. She dropped them off at 12:15 p.m., and said that they would be back to collect them at the end. When she returned, Ashley was still there, but her son had disappeared.Ashley's brother, and others at the pool that day, said Ashley was there for about an hour before she borrowed a friend's cell phone to make a call. Ashley then left the area. Tammy said that many people witnessed her daughter getting into an unidentified vehicle with an older man.Ashley MartinezTammy shared with Dateline that her brother was waiting for me when I returned to the pool on that day. Ashley was gone. She ran away at first. Although it was typical of her, it was not unusual. This didn't feel right.Tammy said that Ashley ran away in 2001 but did not go far. Ashley returned home the next day. Tammy said that she initially believed her daughter had run away from home because of this history. She quickly realized that this was a different time.Ashley had been with her mother for two months when she went to choose a cat to adopt. Ashley adopted Coco, a long-haired grey cat. Tammy shared with Dateline that Coco, her eighth grader at Robidoux School, was happy and very close to her brothers.Tammy thought it strange that Ashley had left behind all her personal possessions, including her daily medication and three pets cats, when she went missing.Tammy, concerned for Ashley's safety, said that she had filed a missing person report with the St. Joseph Police Department. Ashley's friends and witnesses at the pool were interviewed and said that Ashley had discussed running away. She was seen at the pool with Christopher Matthias Hart, 32 years old.Continue the storyHart was repeatedly arrested on unrelated charges in the weeks and months that followed Ashley's disappearance. Sgt. Jason Strong, the current investigator on the case, said that he couldn't comment because it was still open. Hart was not considered a suspect by Strong. Hart was sentenced in Missouri to 15 years for assault and tampering in a motor vehicle. He was released in 2015.A cousin of Harts called the local newspaper News-Press Now in 2017 to claim she had seen Ashley Hart and Hart before Ashley's disappearance, and that they had discussed driving to Oregon. She said that she had originally planned to join them but decided not to.According to News-Press Now: Denise Campbell, an ex-school administrator at Robidoux Middle School, stated in a sworn statement that she had seen the teenager with another man in the fall 2004.News-Press Now verified the authenticity of the affidavits. They reported that it had been notarized by an attorney and signed by a witness, whose name is not clear.Sergeant Strong stated that authorities have been following up on all tips and have used Ashley's DNA to match unidentified bodies in the area. However, no leads have been found.This case has been under investigation for many years and we haven't stopped," Sgt. Dateline was informed by Strong. Although we've been through many dead ends, that doesn't mean we are going to give in.Sergeant Strong said that authorities received recent information which they hope will provide some answers.This week marks 17 year since Tammy last saw her bright smile when she waved her off at a pool. She wants closure now.She is my daughter and I miss her. Tammy stated that I also miss her. However, I know her well and don't believe she would have gone so long without ever speaking to anyone.Tammy stated that her daughter might have put herself in a dangerous position she could not escape from.Tammy spent many years searching online and by phone to find her daughter. Ashley was honored with vigils, races, bike rides, and bike rides. Throughout the past two decades, many searches were made, but nothing has been found.Tammy stated that it has been a 17-year journey. Sometimes, I wonder how shed would look today. Sometimes, I don't want to. She is my happy, bubbly 15-year old daughter.Ashley's family and St. Joseph Parks, Recreation & Civic Faculties Department planted a sugar maple tree at Krug Pool in July 2014. Tammy explained to Dateline that this tree was chosen as its leaves turn red in fall, which is Ashley's favorite color. Ashley's grandmothers came up with the idea for the tree.Ashley's grandmother died earlier this year. The family will now plant another tree in Ashley's honor.Tammy stated that there has never been a time when I didn't think of her or wonder if she is okay. Although I'm not certain she is still alive, I try to keep my fingers crossed.Ashley was fifteen years old at the time she vanished. Last seen in blue jeans, a black top and bikini, with a red cherry print underneath, white Reebok sneakers with red accents and a ring that had two hearts joined together.She was 53 years old and weighed 110 lbs at the time. She was a sandy blonde with blue eyes and had a scar on her right wrist. Her ears, tongue, and naval are pierced. She would have been 32 years old today.Anybody with information regarding Ashley's case should contact the St. Joseph Police Department at 816-271-4777, or 816-271-44747. You can also call the Missouri State Highway Patrol at 1-800-877-352 with tips.