On the morning of December 23, 1974, three girls from three different families set out on a shopping trip together.

Friends Rachel Trlica, 17, and Renee Wilson, 14, planned to go to the Seminary South Shopping Center in south Fort Worth, Texas, to buy some last minute Christmas gifts.

Little nine-year-old Julie Moseley, who lived across the road from Renee’s grandmother, begged to go with them, so the three girls set out together.

They had planned to be home by 4pm at the latest, so Renee could attend a Christmas party with her high school sweetheart, Terry, who was also Julie Moseley’s older brother.

Rachel, the oldest of the three girls, was married to a 21-year-old man named Thomas “Tommy” Trlica. Tommy had already been married and divorced, and he had a two-year-old child at the time. He had also been previously engaged to Rachel’s older sister, Debra.

Debra was living with the couple at the time because she had just broken up with her boyfriend. She later said her’s and Tommy’s was never a “real engagement” and there was no animosity between them.

Rachel had asked Tommy to go with her that day but he had other plans. It was a decision that would haunt him for the rest of his life.

Once they reached the mall, the girls parked their Oldsmobile 98 on the upper level near Sears.

Several people remember seeing the girls at the mall. Renee was wearing a “Sweet Honesty” t-shirt which made her stand out from the crowd.

At some point the girls returned to their car to store some Christmas presents in the backseat and then they simply vanished.

When the girls hadn’t arrived home by 4pm, Rachel’s family drove to the shopping centre where they discovered the abandoned car.

More than 40 years later, investigators still don’t know what happened to the Fort Worth Three.

The morning after their disappearance, Tommy Trlica received a letter in the mail supposedly from Rachel.

The letter read: “I know we’re going to catch it, but we just had to get away. We’re going to Houston. We’ll see you in about a week. The car is in Sear’s upper lot. Love, Rachel”.

Rachel’s family never believed she wrote the letter. They pointed out that the letter was addressed to “Thomas A. Trlica,” when Rachel always referred to her husband as simply “Tommy”.

Six days later, police verified that the handwriting was Rachel’s – but admitted she could have been forced to write the letter.

Clues in the case were few and far between.

It was reported that an elderly woman told three store clerks that she saw a man forcing a girl into a pick up truck on the day of the disappearance. She told the clerks another man and two girls were already in the truck.

Despite numerous pleas from the police, the woman never came forward to make an official statement.

Seven years later, a man came forward to say he saw a man shoving three girls into a van in the parking lot that day.

He said he confronted the man, who told him it was a family matter, and that he should mind his own business.

The case very quickly went cold.

Over the years, the mystery has pitted family against family and brother against sister.

For years, many suspected that Tommy had something to do with the disappearance of his young wife.

Rusty Arnold, Rachel’s younger brother, was just 11 years old when his sister disappeared. He would later suspect that his other sister, Debra, had something to do with the disappearance.

Then this week, more than 40 years later, there was finally some movement in the case.

As the Star Telegram reports, divers retrieved several submerged cars from Benbrook Lake in the hope they might hold some answers to the disappearance.

Rachel’s mother, Fran Langston, was among at least 100 locals who travelled to the lake to witness the moment.

“I wouldn’t have missed this for the world,” she told the Star Telegram. “I hope there’s some evidence in the cars.”

One of the cars was taken to an undisclosed location for analysis.

Rusty Arnold, who was also there, told the newspaper that one of the cars belonged to a person of interest in the case.

“At the same time the girls went missing, we believe the vehicle he was driving also disappeared,” he told the Star Telegram in August. “We sat around coming up with theories, and we discovered that the person of interest lived within five miles of Benbrook Lake at the time. It’s a hunch.”

Something, long submerged in that car at the bottom of the lake, might hold the key to finally solving the mystery of the missing Fort Worth Three.