A serial killer known as the “Grim Sleeper” on Wednesday was sentenced to death for the murders of several women and a teenager — crimes that spanned decades in Southern California.

“I can’t think of anyone that I’ve encountered in all my many years in the criminal justice system that has committed the kind of monstrous, and the number of monstrous crimes, that you have,” Judge Kathleen Kennedy told Lonnie David Franklin Jr.

The 63-year-old Franklin in May was convicted in the 10 murders; Reuters reported at the time that a jury deliberated “just over a day” before returning verdicts.

A jury in Los Angeles finds Lonnie Franklin, Jr. guilty of murdering 10 black women and attempting to murder another in the so-called, "Grim Sleeper" murders (Reuters)

The Los Angeles Times reports that some relatives of victims attended Thursday’s sentencing hearing, at which Kennedy read the names of the 10 who were killed. Franklin “sat stoically” as the sentence came down, the newspaper’s reported.

Relatives also delivered statements at the hearing, including one from a mother whose daughter was among the “Grim Sleeper” victims. The Times reports that the woman, Mary Alexander, addressed Franklin, saying: “I’d like for Mr. Franklin to turn around and face me.”

The Times describes what happened next, when Franklin turned his head and looked at her:

“I’d like to know, why?” Alexander asked, gripping the lectern.
Franklin whispered something in response.
She repeated her question, louder: “Why?”

A police detective later told a reporter that, at this point in the back-and-forth, Franklin had muttered that he “didn’t do it.”

“I know she didn’t do anything to hurt you,” Alexander told Franklin, “I know that.”

Authorities have said that Franklin murdered 10 women, including the teen, from the mid-1980s to 2007, though investigators believe he might have killed more victims. It took years for investigators to identify him as the suspect, a process aided by DNA analysis.

“This defendant is completely irredeemable,” Deputy District Attorney Beth Silverman wrote in her sentencing brief, according to the Associated Press. “He is a psychopathic, sadistic serial killer who takes joy in inflicting pain on women and killing them.”

The 2014 documentary "Tales of the Grim Sleeper” examines the story of Lonnie Franklin Jr. Franklin is thought to have killed over one hundred victims. (Nick Broomfield/HBO Documentary Films)

Franklin was also convicted of attempted murder for an attack on another woman, who testified at his trial. That woman, Enietra Washington, said Franklin shot, sexually assaulted and took a photo of her before he pushed her out of an orange Ford Pinto in 1988.

The “Grim Sleeper” nickname is a nod to the lengthy gap in the slayings. Seven women were killed between 1985 and 1988, and three more were killed between 2002 and 2007. Franklin was arrested in 2010.

DNA evidence helped link him to the killings. The Times  has previously reported that police had urged the state to look for DNA matches that could be related to the killer, and got approval from Jerry Brown, who was California’s attorney general at the time. That led them to Franklin’s son.

An undercover officer then collected DNA from Franklin, a former garbage collector. The officer posed as busboy at a pizza parlor, where Franklin was attending a birthday party, and snagged items that led to his arrest. Police said uneaten pizza, a napkin and a drinking glass gave him away, according to the Times.