The Palm Beach County Sheriff's Office says that on May 26, 1990, Marlene Warren was home with her son and some of his friends when a vehicle pulled into the driveway around 10:45 a.m.
Marlene Warren, 40, was shot at least once in the head by the clown wearing a red wig, a red bulb nose, gloves and a smile painted on its white face.
On Tuesday, Sheila Warren was located in Washington County Virginia and arrested without incident. The two are said to have been living in Tennessee where they owned and operated a restaurant together.
At the time of his wife's shooting death, Michael Warren was driving to a casino in Miami, the Palm Beach Post reported.
But Michael Warren had been having an affair with Sheila Keen, a then-27-year-old recent divorcée who repossessed cars for his dealership, according to the Sun-Sentinel, which covered details of the sprawling homicide investigation in 1990.
The Palm Beach County Sheriff's Office says Keen, the mistress of the victim's husband, was a suspect early on, but there was never enough evidence to charge her.
PBSO Detectives received assistance from the Palm Beach County State Attorney's Office, U.S. Marshal's Task Force Western District of Virginia, Detectives from the Washington County Virginia Sheriff's and the Tennessee Bureau of Investigations.
Officers arrested Warren 27 years later at her home in Abingdon, Va. The clown gave her the flowers and balloons.
Marlene's son Joey remembers saying "how pretty" the flowers were as the gift was handed over to his mum before she was gunned down in Wellington, Florida. After calling 911, he got his keys, got into a auto and tried to find the Chrysler convertible to no avail.
A white Chrysler convertible had been found abandoned on Royal Palm Beach, which matched Aherns' description, reports said at the time.
The balloons that the clown carried were only sold at a Publix at Community and Military Trail, near Sheila Keen's home, according to the investigators. The salesperson described the woman who bought the items as having long, brown hair, like she had. Store clerks picked her out of a lineup and police found fibers from a bright, orange wig in Keen Warren's home.More news: United Nations chief urges to eliminate existing nuclear arsenals