A former East Baton Rouge Parish coroner testified Saturday at Jeffery Lee Guillory’s murder trial that it is possible Renee Newman was strangled with her own T-shirt in 2002 but unlikely her killer used a zip tie.

Prosecutor Dana Cummings asserts Guillory, a suspected serial killer, strangled Newman with the shirt she was wearing when her body was found April 11, 2002, in landscaping behind the old Maison Blanche/Goudchaux’s building on Laurel Street.

Cummings says Guillory’s DNA was discovered on Newman’s shirt.

Guillory’s attorneys contend — but are barred from arguing to the jury — that convicted Baton Rouge serial murderer Sean Vincent Gillis, who used nylon zip ties to kill some of his victims, associated with Newman, 46, also of Baton Rouge, and may have strangled her.

State District Judge Tony Marabella ruled Thursday — just before the start of Guillory’s second-degree murder trial in Newman’s death — that the defense could not mention Gillis during the trial.

The state 1st Circuit Court of Appeal let that decision stand late Friday. Marabella made reference to the appeal court’s ruling just before the start of Saturday’s proceedings. The jury was not in the room when he did so.

Dr. Louis Cataldie, who was coroner of East Baton Rouge Parish in 2002, testified as a prosecution witness that he went to the Newman crime scene but did not perform her autopsy. Cataldie said Newman’s cause of death was due to strangulation, and he noted she had three ligature marks on her neck.

When Newman’s body was found, her shirt was pulled up above her bra, according to a crime scene videotape shown previously to the jury.

Cataldie said a “significant amount of force’’ was used to cause Newman’s injuries and death.

When Sonya Hall, one of Guillory’s attorneys, asked if a zip tie could have caused the ligature marks on Newman’s neck, Cataldie said it is not likely because a locked zip tie would have left much longer marks.

Cataldie added it would be difficult to strangle someone with an unlocked zip tie, a type of fastener widely used for binding electronic cables or wires together.

When Hall asked if some other object could have been used to strangle Newman, the ex-coroner replied, “Yes, absolutely.’’

Later, Cataldie told Cummings it is “still a possibility’’ that Newman was strangled with her own shirt.

Guillory was arrested in December 2009 and booked in the murders of Newman and two other Baton Rouge women — Florida Edwards and Sylvia Cobb, both 36.

Marabella is allowing Cummings to introduce evidence related to the Edwards slaying. The prosecutor alleges the killings show Guillory’s pattern.

“Neither one of these women were strangled by a zip tie,’’ Cummings said during the lunch break.

“We do not believe the T-shirt was the murder weapon’’ in the Newman killing, countered Franz Borghardt, one of Guillory’s attorneys.

Courtroom fireworks erupted while Cataldie was testifying about the 1999 death of Edwards.

Authorities have said Newman and Edwards led high-risk lifestyles.

Hall asked Cataldie if he or Baton Rouge police have referred to certain murder victims as “throwaways,’’ which prompted Cummings to spring from her seat and say in a loud voice, “Excuse me?’’

After the jury was excused from the courtroom, Cataldie — the author of a book that includes the term “throwaway’’ — said he personally does not use that term.

“She’s a human,’’ he said of Edwards. “I don’t have a definition’’ for the term “throwaway.”

Marabella said it is his understanding that the book makes reference to some of Gillis’ victims.

“I ruled Sean Gillis is not part of this trial,’’ the judge said in a stern voice. “We are not going there.’’

Borghardt told reporters, “We weren’t trying to bring up Gillis.’’

“That term is just so offensive,’’ Cummings said of the word “throwaway.’’

Guillory faces an automatic sentence of life in prison if convicted as charged in the killing of Newman.

He already is serving a 50-year prison term in the second-degree robbery and attempted second-degree murder of a woman in Lafayette in late 2007. He was found guilty in that case early last year.

The victim in that case is scheduled to testify Sunday. The trial could conclude Monday.