For retired detective, arrest in decades-old case of killer clown is a relief

— -- Retired Florida Det. Louis Sessa finally got the phone call he'd been waiting for Tuesday: A suspect had been arrested in a cold-case killing that had haunted him for nearly three decades.

"They notified me last night she was going to be arrested," Sessa told ABC News, referring to 54-year-old Sheila Keen Warren, who was taken into custody Tuesday.

Twenty-seven years earlier, a clown walked up to the front door of Marlene Warren's Wellington, Florida, house and fatally shot her. Sessa had long suspected Sheila Keen Warren, who later married Marlene Warren's widower, Michael Warren, to be the killer but couldn't prove it.

Despite retiring in 2006, Sessa always stewed on the unsolved cold-blooded clown murder.

"Even after 27 years the case never goes away," he said. "It was a big relief for me to hear she was in jail."

He's not alone.

For Marlene Warren's parents, the news was welcome but opened old wounds.

"They finally found someone," Marlene Warren's mother, Shirley Twing, told ABC News. "Now all they have to do is put her away and anyone else that was helping her.”

The deceased woman's stepfather was overcome with emotion.

"It’s bringing a whole lot back..." Bill Twing said, taking a long beat. "It’s sadness but good sadness. They found somebody hopefully.”

Amid the rush of emotion, there was some cautious optimism for both of them.

“I haven’t been this sad in a long time, but it’s a big load off my back,” Bill Twing said.

Marlene Warren's son, Joseph Ahrens, who was 22 when the crime occurred and is now 49 and living in Iowa, told ABC affiliate WPBF that the news was a "big shock" and upon hearing of the arrest was "happier than I've been in many years."

Sheila Keen Warren is in custody in Washington County, Virginia, according to the Palm Beach County Sheriff's Office. Police have not said whether her husband, Michael Warren, was involved in his ex-wife's death.

Michael Warren was arrested in late 1990 following the murder of his wife on several unrelated racketeering charges. He served a three-year prison sentence, court records show.

According to the sheriff's office, Marlene Warren was at her home on May 26, 1990, when she answered her front door and was met by a clown carrying a flower arrangement and two balloons. A gunshot rang out, and Marlene Warren fell to the ground, witnesses told officials.

The clown then walked back to a vehicle parked in the driveway.

Two days later, Marlene Warren died at a hospital.

The case heated up in 2014, when the Palm Beach County Sheriff’s Office Cold Case Unit reopened the homicide investigation.

"Witnesses were re-contacted and additional DNA analysis was conducted," the sheriff's office said in its release. "It was also learned that Sheila Keen had married Michael Warren, Marlene Warren’s husband, in 2002. Both had been living in Tennessee operating a restaurant together. As a result of the investigation, probable cause was established linking Sheila Keen Warren to the murder of Marlene Warren."

In late August, new evidence was presented to a grand jury, eventually leading to an arrest warrant for first-degree murder for Sheila Keen Warren.

Sessa wouldn't say what the new evidence was, but he did mention that "DNA evidence comes into play in cases like this."

"That type of technology wasn’t available years ago," he said.

In a hearing this morning, Sheila Keen Warren waived extradition back to Florida but authorities said it could be up to 10 days to execute her return. it is unclear whether she has an attorney.