Suspected serial killer Jeffery Lee Guillory, described by a prosecutor as “cold through and through,’’ was convicted Sunday evening of second-degree murder in the 2002 strangulation of Renee Newman, of Baton Rouge.

An East Baton Rouge Parish jury of six women and six men deliberated for just over 50 minutes before returning its unanimous verdict.

Prosecutor Dana Cummings said she was “pleasantly surprised’’ by how quickly the jury reached the verdict. She said strong DNA evidence played a big part in the swift guilty verdict.

District Attorney Hillar Moore III said justice, albeit delayed, was served.

“This is the proper outcome,’’ he said.

Guillory, 45, faces an automatic sentence of life in prison.

He will be formally sentenced Nov. 10.

Guillory’s lead attorney, Franz Borghardt, said an appeal will be filed after the sentencing.

Borghardt said he wished he could have argued to the jury that Newman, 46, also associated with suspected serial killer and convicted Baton Rouge murderer Sean Vincent Gillis, but he was barred from doing so.

“Obviously it would have been nice to put on a defense of our choosing,’’ he said.

Newman’s body was found April 11, 2002, behind the old Maison Blanche/Goudchaux’s building on Main Street.

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

Edwards was killed in 1999. Cobb was slain in 2001.

Cummings said Guillory will not be prosecuted further.

Guillory already is serving a 50-year sentence in the second-degree robbery and attempted second-degree murder of Johnnie Rose Martinez, of Lafayette, in December 2007. He was found guilty in that case early last year.

Martinez testified Sunday for the prosecution at Guillory’s trial.

State District Judge Tony Marabella decided earlier this year that prosecutors could use Guillory’s conviction in the Lafayette case, and his arrest in the Edwards slaying, at his trial in the killing of Newman.

Marabella ruled the 1999 and 2007 crimes are “so similar’’ to the 2002 crime that “the same person can be said to have committed the crimes.’’

Edwards’ body was discovered Sept. 3, 1999, inside the old Dynasty Lounge on North Boulevard. She also died of strangulation.

Cobb’s body was found July 25, 2001, inside an abandoned house on North Acadian Thruway West. She was beaten to death.

In her closing arguments to the jury, Cummings said Guillory epitomizes “cruelty and cowardice’’ and should be “locked away.’’

“He’s cold through and through,’’ she said. “He’s a coward because he picks on women he thinks society doesn’t care about.’’

Police have said Newman and Edwards lived high-risk lifestyles.

Cummings reminded jurors Guillory’s DNA was found on Newman’s shirt that was pushed up around her neck, as well as on her bra and breasts and under her fingernails.

“She tried to fight back,’’ the prosecutor said.

Cummings called Newman’s T-shirt the murder weapon.

Borghardt disputed that contention and acknowledged the state proved Guillory came in contact with Newman and Edwards, but, he said, it could not be shown when his DNA was deposited on them.

A Louisiana State Police DNA analyst testified during the trial that there is only a 1-in-9.76 quadrillion chance that the DNA found on Newman’s and Edwards’ bodies belongs to someone other than Guillory.

Guillory twice denied — in 2006 and again in 2009 — knowing or ever seeing Newman and Edwards.

Guillory already was in custody when he was arrested in the killings of Newman, Edwards and Cobb.

He was arrested in January 2008 after police identified him from a photograph taken at a Baton Rouge bank ATM where he was seen using a credit card stolen from Martinez. He has been in jail ever since.

Martinez on Sunday identified Guillory as the man who severely beat and robbed her after dragging her into a wooded area near the Walmart store on Evangeline Thruway on the evening of Dec. 29, 2007.

She said she survived the attack by playing dead.

Guillory remains a suspect in several other unsolved killings of women in Baton Rouge that occurred in the late 1990s and early 2000s, authorities have said.