On Monday, September 17, 1984, Vicki asked and received permission from her mother, Debbie Carlson, to ride her bike to a mailbox to post a birthday card to her aunt. This was the first time Carlson had allowed any of her children to go out on their own, previously using the buddy system. After 20 minutes, Carlson sent Vicki's 11-year-old sister Stephanie to look for her; Stephanie found Vicki's bike lying on the side of the road a few blocks away, and one block from the elementary school. Carlson placed Vicki's bike in her car trunk and called the Pima County Sheriff’s Department. Detective Gary Dhaemers responded, and a few hours later a command center was set up.
After interviews with possible witnesses, Sam Hall, a coach at an elementary school, stated he saw a suspicious-looking driver parked in a vehicle in an alley beside the school on September 17. Hall had been supervising a group of students at play when he noticed a suspicious vehicle. According to Hall, the driver was making strange gestures and was struggling with his stick shift. He memorized the licence plate, ran to his car to get a notepad and wrote it down. He later gave it to police after hearing Vicki went missing. A little girl said the driver made an obscene gesture to her as he cruised by her house. Another saw the driver back into a telephone pole.
The trace on the license plate led to a 28-year-old Los Angeles man named Frank Jarvis Atwood. Agents ran a background check and found kidnapping and child molestation charges. Frank Atwood was out on parole in California. They went to the address where Atwood's car was registered. It was the home of Atwood's parents, Frank Jarvis Atwood Sr., a retired army brigadier general and his wife. A few hours later, Atwood called his parents stating his car had broke down in Texas and he needed money wired to get it fixed. His mother wrote down the address in Kerrville, Texas, where Atwood awaited a new transmission. His father then drove to a nearby payphone and reported the address to the FBI. Agents from the FBI's Texas Bureau detained Atwood and his traveling companion, James McDonald, at the mechanic shop on September 20 and impounded the car.
During questioning, Atwood told investigators he was in Vicki's neighborhood on September 17, the day she disappeared, staying in a nearby park. About 3:00 PM, he left to buy drugs and returned to the park about 5:00PM, but did not say where he was during the two-hour period. McDonald corroborated Atwood's story, and told investigators that he and Atwood had an argument in the park about 3:00. After that, Atwood left for two hours and returned with bloodstains on his hands and clothing. Atwood told McDonald he got into a fight with a drug dealer and stabbed him. Investigators found two men who claimed Atwood spent two nights in their trailer. One of them, known as Mad Dog, claimed Atwood's clothes and hands were bloodstained, and that they had suggested Atwood get rid of his clothes. Atwood told them that he stabbed a double-crossing drug dealer.
While no physical evidence in the car could be linked to Vicki's person, accident reconstruction experts matched pink paint on the front bumper of Atwood's vehicle to the color of the paint on Vicki's bike, and traced damage to the car's gravel pan to one of the bike's pedals. Traces of nickel plating from the bumper were also found on the bike. Returning to the site where the bike was found, investigators discovered damage to the mailbox post about 12 inches above ground, consistent with the height of Atwood's sports car, and believed this to be the spot where the car allegedly struck Vicki's bike at a slow speed. Atwood's alleged bloodstained clothing from the day of Vicki's disappearance was never recovered.
Ten days after Vicki's disappearance, Atwood was arrested and charged with one count of kidnapping. A month after Vicki's disappearance, Atwood returned to Arizona to stand trial. Because of the publicity of the case in Tucson, the trial was moved to Phoenix. Jury selection took almost 6 weeks, and bail was denied. On December 3, 1984, Atwood pleaded not guilty to kidnapping charges.
On April 12, 1985, a hiker found a small human skull in the Tucson desert, about 20 miles (32 km) from where the bike had been found. The skeleton had been scattered by animals. Due to the state of the remains, the cause of death could not be determined, nor whether the child had been sexually abused. Dental records confirmed they were Vicki's remains. Traces of adipocere found on the skull fixed the time that the body had been placed in the desert to within 48 hours of Vicki's disappearance. Atwood was indicted and found guilty of first degree murder, and was sentenced to death on May 8, 1987.
During his years on death row, Atwood has "gotten married, been baptized in the Greek Orthodox Christian church, obtained two associate degrees, a bachelor's degree in English/pre-law and a master's degree in literature. He has written six books, five of which have been published. He's also working with people on the outside to create a website". As of 2012, he was one of the longest-seated prisoners on death row. He claims that police tampered with the evidence found on his car, and that no physical evidence has been found placing Vicki in his car. His ongoing appeals for judicial re-review of his case have been denied.
After her daughter's murder, Debbie Carlson became a victims' rights activist. She helped establish a victims' advocacy group called "We the People"; worked for the passage of Arizona's Victims' Bill of Rights, which was passed in 1990; and helped institute Southern Arizona's Amber Alert system in 2000.