It's been nearly three decades since a clown bearing a bouquet of carnations and two balloons shot Marlene Warren at her Florida home on May 26, 1990

It’s been nearly three decades since a clown bearing a bouquet of carnations and two balloons shot 40-year-old Marlene Warren in the face in the doorway of her Florida home, leaving her to die.

For years the May 26, 1990, slaying in wealthy Palm Beach County went unsolved and the killer clown went unidentified — that is, authorities say, until now.

Armed with new DNA evidence, investigators arrested Sheila Keen Warren on Sept. 26 about a mile from her home in Abingdon, Virginia, where she was living with Michael Warren, Marlene’s widower, whom Sheila wed in 2002.

Charged with first-degree murder, Sheila was extradited on Oct. 3 to Palm Beach County, Florida, and is being held without bond while awaiting trial. She appeared in court on Monday and is scheduled to return in January for a status hearing.

She has not yet entered a plea. Her attorney, Richard Lubin, has said she “vehemently denies” murdering Marlene. Sheila, he tells PEOPLE, “is not going to plead guilty and is not guilty.”

Prosecutors are pledging to seek the death penalty if Sheila is convicted.

Marlene’s mother, Shirley Twing, 87, says she is relieved her daughter’s alleged killer has finally been caught.

“I hope justice is served,” she tells PEOPLE. “It’s been 27 years.”

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Authorities suspect that Sheila Keen Warren (left) dressed like the clown “Bozo” to fatally shoot Marlene Warren in May 1990 at Marlene’s home in Wellington, Florida.
| Credit: Palm Beach County Sheriff's office/Palm Beach Post via AP; Margaret Norton/NBC/NBCU Photo Bank via Getty
Clown MurderPalm Beach Post
Marlene Warren
| Credit: Palm Beach Post

Authorities say they had long suspected Sheila, who is now 54 and going by the name Debbie: Not only did she work for Michael, repossessing cars at his used car dealership, she was also rumored to be his mistress.

Although investigators said they found evidence at her home, they were unable to arrest her, citing a lack of probable cause, Palm Beach County Sheriff Ric Bradshaw tells PEOPLE.

But the case was reopened in 2014 and advances in DNA technology ultimately led to Sheila’s arrest, Bradshaw says.

Until her arrest, Sheila and Michael, now 66, lived a comfortable life, spending weekends with friends at their lakeside home in Abingdon, Virginia. (Michael, who could not be reached for comment, has not been implicated in Marlene’s death and authorities won’t comment on his status in the ongoing investigation.)

As the years went on, the couple seemed as in love as ever — with Michael writing on Facebook in 2013 that he couldn’t wait to get home and “be back in my baby’s arms.”

Marlene’s family, on the other hand, has spent years without their “special girl.”

Says stepfather Bill Twing, 75: “Everyone got robbed when she was killed.”

• With reporting by LINDA MARX