LOS ANGELES — Four strikingly similar attacks on women in California and Illinois were all planned and executed by a skilled serial killer who studied the lives and homes of victims who lived near him before savagely stabbing them, a prosecutor said Tuesday.

Los Angeles County Deputy District Attorney Garrett Dameron in his closing argument tried to establish that the killings of three women and the attempted killing of a fourth who fought him off were all the unmistakable work of 43-year-old Michael Gargiulo.

All the attacks were bold but stealthy, Dameron said, coming at night inside or just outside the women’s homes by a man with knowledge of the residences and the surrounding neighborhood, knowledge of the life patterns of the victims, and knowledge of how to kill quickly and cover his tracks.

“Those similarities point to one man, one killer: Michael Gargiulo,” Dameron said.

The killings involved dozens of deep stab wounds delivered by a strong man, Dameron said. In none of the cases was there evidence of a fight that preceded the stabbing, nor were the victims robbed or sexually assaulted, though prosecutors have alleged that Gargiulo got a sexual thrill from the brutality of the killings. In none of the attacks was a murder weapon found. And all the victims were left in the spot where they were killed.

“These were monstrous, torturous attacks, all four,” Dameron said. “This was someone that was going to take pleasure in plunging a knife into their victim over and over.”

The prosecution wrapped up its presentation Tuesday afternoon and Gargiulo’s lawyers will make their closing argument on Wednesday, when they will likely remind jurors of the dearth of forensic evidence directly tying Gargiulo to the two Southern California killings. He has pleaded not guilty.

Dameron said Tuesday that evidence is lacking in some areas because Gargiulo was an expert at getting rid of it, and had researched the subject, according to former friends, girlfriends and co-workers who testified during the trial.

The prosecutor said Gargiulo’s track-covering has forced authorities to rely on establishing connections between the killings along with other circumstantial evidence, but argued that that evidence remains overwhelming.

Dameron began his presentation with a tribute to the case’s only surviving victim, Michelle Murphy, who used her “strength and courage” to fight off the much-larger man who attacked her as she lay in bed in her Santa Monica apartment in 2008, an act that would lead to Gargiulo’s arrest and eventual charges in three killings dating back to 1993.

“Eleven years ago, a 26-year-old woman had the strength and courage to fight off a killer,” Dameron said. “Thanks to her toughness, not only was she able to survive, but she forced her right-handed attacker to cut himself, leaving a blood trail, and leading investigators to answers they’d been seeking for 15 years.”

Murphy was the first witness jurors heard in the three-month trial, which also included the testimony of Ashton Kutcher, who was 23 when he was supposed to have drinks with fashion-design student Ashley Ellerin on the night she was stabbed to death at her Hollywood home at age 22 in 2001. Kutcher testified that he arrived very late, looked through Ellerin’s window and saw stains that he assumed were spilled wine, and left because he thought she had gone out without him.

Gargiulo is awaiting trial in Illinois for the killing of Tricia Pacaccio in 1993 when he was 17 and friends with Pacaccio’s younger brother. Prosecutors were allowed to present evidence of the case in his California trial to help establish a pattern between the killings.

He’s also charged with the murders of Ellerin and Maria Bruno, who was stabbed to death at age 32 at her home in the Los Angeles suburb of El Monte in 2005, and the attempted murder of Murphy.

The three murder cases were going increasingly cold until the attack on Murphy set off a chain of events that led to the arrest and charges against Gargiulo, who was living very near each of the women at the time they were attacked.

DNA matching Gargiulo was found via his blood on Murphy’s bed, under Pacaccio’s fingernails, and on a shoe-covering bootie, which Gargiulo used in his work as an air-conditioning repair man, near Bruno’s apartment, though Gargiulo lived in the same complex.

Gargiulo’s charges include special circumstances allegations of multiple murders, lying in wait before killing and using deadly weapon, making him eligible for the death penalty.

This story has been corrected to reflect that the deputy district attorney who made closing arguments was Garrett Dameron, not Dan Akemon.