SALT LAKE CITY (ABC4) – All it took was twenty minutes for Nancy Baird to vanish.

On the 4th of July in 1975, Baird disappeared from where she was working.

At around 5:10 p.m. Baird was behind the cash register when someone left the Fina gas station in east Layton.  At around 5:30 p.m. the store manager arrived but didn’t see Baird anywhere.

Former Davis County sheriff, William “Dub” Lawrence, and his deputies arrived after being summoned.

“All of her belongings were there,” said Lawrence who has long retired. “Her purse was there. Her car keys were there. Her vehicle was there. Her purse, money.”

Baird lived nearby and had a four-year old child and was divorced. Her son was staying with relatives.  At the time, her former husband, Floyd Baird was in Wyoming when she went missing.

“(Husband) was pulled over by highway patrol and they told him about the situation and he was pretty upset about it,” said Wally Baird, his brother.

“It was kind of shocking. We heard a lot of things, theories, rumors.”

Authorities questioned persons of interest who came to the gas station during that twenty-minute gap. They used credit cards to pay for the gas and left according to Lawrence.

As days of her disappearance passed, the FBI was called in.

Nearly a month later, authorities still didn’t have a clue as to her whereabouts.

“We couldn’t find anybody that didn’t have an alibi, a good explanation where they were,” said Lawrence. “(There was) no evidence, no victim. It was one of those things that we had nothing to go on. Nothing.

Baird’s murder remained a mystery and her remains were never found. In 2015, a discovery was made.

Davis County sheriff deputies were dispatched to an area along Highway 89 near Fruit Heights.  Someone had found a human skull.  It was determined to be a female skull.

Wally Baird recalled the family’s interest peeked when they learned of the skull’s discovery.  They waited and waited to learn more.

“It was something that if it involved Nancy that they would have put something on the news,” he said.

But they never received word.  Months later, authorities learned the skull belonged to Theresa Greaves, who went missing in 1983.

In August, 1975, authorities realized other young women were also disappearing during the time Baird disappeared.

“There were several of those bodies that just disappeared into thin air.

Authorities in Davis County had their first clue about a possible suspect in Nancy Baird’s disappearance.

Tomorrow, in part two, a serial killer emerges.