It was the night of the Grammy Awards in Hollywood, and 22-year-old Ashley Ellerin had a date with Ashton Kutcher.

The fashion school student and part-time stripper lived in a charming yellow bungalow in a neighborhood just behind the famous Grauman’s Chinese Theatre on Hollywood Boulevard. That night, Feb. 21, 2001, she and Kutcher, then starring in “That ’70s Show,” had plans to go to a post-Grammy party. But Ellerin wasn’t picking up.

Kutcher thought maybe he had bad reception, as he would later tell Los Angeles police detectives, LA Weekly reported, and so he started driving to her house anyway. Her lights were on and her maroon BMW was parked in the driveway when he pulled in. He knocked on the door, and kept on knocking, and still there was no answer. He thought maybe she was upset with him, that she had “brushed him off,” police would later say.

But as he started to leave, he happened to peer into a window, and he noticed something odd: a trail of red stains on the carpet, leading to her bedroom. He thought it was spilled wine.

Instead, as prosecutors will tell a jury this week, it was the aftermath of a brutal stabbing — and the work of Michael Gargiulo, a suspected serial killer whose alleged murders span two states and 15 years. In Los Angeles, he is known as the alleged “Hollywood Ripper.”

Now, more than 18 years after prosecutors say Gargiulo stabbed Ellerin 47 times in her bedroom, he is finally standing trial in her death this week. Gargiulo is charged with two counts of murder and one count of attempted murder in the 2008 attack of a third woman, who police say managed to fight him off. Thousands of miles away, in Chicago’s Cook County, Gargiulo, 43, is also expected to stand trial in the 1993 stabbing death an 18-year-old woman, who is believed to be his first victim.

Between 1993 and 2008, Gargiulo is suspected of preying on young women and in some cases using his job as an air-conditioning repairman to gain entry into their homes and lives, only to stalk them and wait for a chance to ambush them in the middle of the night at their own homes. During opening arguments Thursday, prosecutors described it as “the methodical and systematic slaughter of women,” the Associated Press reported.

Prosecutors say the cases all have one thing in common: He lived right in the same neighborhood as his victims — in some cases right across the street. They called him “the boy next door killer,” the AP reported.

"What you will hear is that Michael Gargiulo, for almost 15 years, was watching, always watching,” prosecutor Daniel Akemon said, according to the AP. “And his hobby was plotting the perfect opportunity to attack women with a knife in and around their homes.”

The trial is expected to last six months, and Kutcher may be called to testify as a witness, the Los Angeles Times reported. Gargiulo’s defense attorney, Daniel Nardoni, told jurors that there is “not one single bit of physical evidence” tying Gargiulo to Ellerin’s death, KABC reported. Gargiulo has insisted he had nothing to do with any of the stabbings.

“I’m 100 percent innocent,” he told CBS’s “48 Hours” from jail in 2011.

The chilling saga began on the morning of Aug. 14, 1993, when Tricia Pacaccio’s father walked outside with a cup of coffee and saw two white tennis shoes poking out where they didn’t belong, as he told “48 Hours.” He collapsed when he saw the rest of the picture: his daughter lying lifeless and bloody on the side-door stoop, still holding the house keys.

For years, police would struggle to find any physical evidence or any promising suspects. But one name kept popping up: Michael Gargiulo, who was 17 at the time and lived down the street.

Known for a having short fuse, he hung around with Pacaccio’s brother and had been to the house on a number of occasions. But in the aftermath of Pacaccio’s death, his behavior struck the family as bizarre, as they told "48 Hours.” Although he was not a close family friend, he started buying her parents presents: flowers for Pacaccio’s mother, Diane; a shirt for her father, Rick. He tried to pin the murder on a friend when questioned by police but later recanted his story when asked to present it before a grand jury, Chicago magazine reported.

The only real break in the case finally came a decade later, in 2003, when DNA detected on Pacaccio’s fingernails was found to match Gargiulo.

By then, Ellerin was already long dead.

Police told “48 Hours” they believe Gargiulo fled to Los Angeles around 1999 when he realized authorities were taking a closer look at him in Pacaccio’s death. He moved into the same Hollywood neighborhood as Ellerin and, one day in the fall of 2000, introduced himself to her while she was trying to fix a flat tire. He offered to help, adding that he was also an air-conditioning and furnace repairman if she and her roommate ever needed a hand. Turns out, they did.

The more Gargiulo came by for maintenance, the friendlier he got with Ellerin, so much that he came over for a party she hosted, LA Weekly reported. Described as a “braggart and bull---- artist” by one detective, Gargiulo liked to thrill her and her roommate, Justin Peterson, with mostly invented tales of his glamorous life as a professional boxer, the films he’d been in and stars he’d met, the time he was electrocuted on the job.

Even the one about how authorities in Chicago were investigating him for a murder.

He saved that one for Peterson, revealing it the day after Peterson spotted him sitting in his car outside their home at 3 a.m. When Gargiulo came by for some more heater repair work, Peterson confronted him.

“I said, what the hell were you doing outside my house at 3 in the morning?” Peterson recounted to “48 Hours.” “He said he couldn’t go home because the FBI was waiting for him to collect DNA samples — some murder from Chicago. His best friend’s girlfriend was murdered or whatever. And I said, ‘Well, what do you have to hide?’ ”

Peterson and others would immediately identify “Mike the furnace man” as a suspicious acquaintance in Ellerin’s life when police began investigating her death. Kutcher, whom she’d only just started seeing, was quickly ruled out as a suspect.

As Los Angeles police were investigating Gargiulo, something strange happened: Chicago police called. They wanted to know if police in the Hollywood division could obtain a DNA sample from an area man named Michael Gargiulo — a person of interest in the murder of Tricia Pacaccio. At that moment, Hollywood homicide detective Tom Small told Chicago magazine, “bells and whistles went off.”

“The type of attack was similar," Small told the magazine. “The type of victim was similar. The type of weapon, the manner and method of the attack — everything is so similar that we all believed it’s gotta be our guy.”

Yet, even when the DNA sample that Los Angeles police obtained from Gargiulo came back as a match to the DNA found on Pacaccio’s fingernails, Chicago authorities did not feel they had enough evidence to charge Gargiulo. And given there was no physical evidence at the Ellerin crime scene, Small couldn’t charge him so quickly either. Explaining its reasoning to numerous news outlets, the Cook County State Attorney’s Office said it was still possible that Gargiulo’s DNA landed on Pacaccio’s fingertips because of “casual contact."

Small — not to mention Pacaccio’s parents — was furious.

“Stupid me, I thought they [were] going to arrest him, confront him with evidence and see what he had to say,” he told Chicago magazine. “That’s what I thought, but it didn’t work out that way.”

Instead, California prosecutors say, Gargiulo went on to brutally attack two more women, killing 32-year-old Maria Bruno in El Monte, Calif., in 2005, and critically injuring 27-year-old Michelle Murphy in Santa Monica in 2008. Both of them were ambushed while lying asleep in their own beds in the middle of the night.

And both of them lived directly across from the Gargiulo, who could peer through their windows when the blinds were open, authorities said.

“It troubles me enormously,” a former Chicago homicide detective told Chicago magazine. “Those young women in California are dead because we dropped the ball.”

Bruno, a mother of four, was stabbed 17 times in the middle of the night, in December 2005. A blue medical bootie was found just outside on the pavement — though it would be three years until police would find the other one.

Not until after Michelle Murphy, the lone survivor, fought for her life one night in April 2008.

She awoke to a knife plunging into her chest, Santa Monica homicide detective Richard Lewis told “48 Hours.” She started grabbing for it, the knife slicing through her hands. She was bleeding from wounds in her right arm and her shoulder and her torso. But amid the struggle, her attacker cut himself. Murphy seized the moment. She lifted her knees to her chest, then used her feet to catapult the attacker off her bed, Lewis said. He fell backward and stumbled onto his feet.

Turning to leave, he said, “I’m sorry.”

The trail of blood Gargiulo left on his way out would identify him as the suspected killer, Lewis said. He was arrested on charges of attempted murder in June 2008. Police in El Monte, recognizing the similarities to Bruno’s attack, reinvestigated and discovered that sure enough, Gargiulo lived across from Bruno. They said they found the second blue bootie in the attic of his since-vacated apartment. In September 2008, police charged him with Bruno’s murder as well as Ellerin’s.

It would be another three years, however, until Cook County prosecutors charged Gargiulo with killing Pacaccio all those years ago. Two of Gargiulo’s former friends saw the “48 Hours" episode, prompting them to come forward to prosecutors as key witnesses. They remembered he had told them a tall tale about the time he killed a girl on her doorstep in Chicago, they would later tell the news station.

As with many of the tall tales he told, the two men didn’t believe it.