His Killer Thought He Was ‘Dexter’

Before stabbing 17-year-old Lucas Cavanaugh to death, his killer texted ‘fantasies’ about his ‘uncontrollable desire’ for blood.

Photo Illustration by The Daily Beast

During his junior year of high school, Matthew Fischer stabbed a love rival to death after they sparred via text message over a girl. “Mom, I killed somebody,” the South Carolina student said over the phone, moments after a brawl outside the girl’s house.

Fischer told detectives that Lucas Cavanaugh, a 17-year-old buddy of his girlfriend, “wouldn’t stop” beating him and was “relentless” that evening in January 2015. He claimed he knifed Cavanaugh in self-defense—disemboweling him—before walking away from the horrific scene to call his mom.

“A kid named Lucas. He wouldn’t stop coming at me. I did not have a choice,” Fischer told her, according to his interview with police.

Fischer asked his case to be dismissed under the state’s “stand your ground” law, claiming that Cavanaugh started the fight in Mount Pleasant. He said Cavanaugh choked and beat him and that he was forced to draw the knife in self-defense.

But last week, a Charleston County judge ruled Fischer must stand trial for murder, citing conflicting testimony from the accused teenage killer.

Part of that testimony involved a series of disturbing texts from Fischer to his girlfriend that described his “murderous urge”—messages his attorney told The Daily Beast were “fantasy” and akin to the TV show Dexter.

Weeks before the stabbing, Fischer spun a dramatic and violent yarn about a rapist who supposedly attacked him and his sisters when they were children and living in Oklahoma. And he discussed getting revenge by torturing and mutilating “the guy who made me want to kill,” according to texts reviewed by The Daily Beast.

“Ever since I could remember, I had an uncontrollable desire to kill whoever hurt the people I love. And I never knew why. But then last year I got a letter from him. Then the entire night came back,” Fischer wrote to his girlfriend, Natalie Brown, in December 2014.

“I was 2. Oklahoma. No one was home except me and my 2 sisters and a baby sitter. It was dark. Cold. Then at 10 that’s when he came in upstares [sic]. Quiet, no one knew,” Fischer continued.

The then-16-year-old described how his babysitter was tucking him in when the assailant stabbed her in the back.

Fischer later admitted in court the tale was bogus.

Fischer’s lawyer, Andy Savage, said prosecutors tried to portray his client as “someone with violent tendencies” by introducing the text messages in court last week. But he argued that Fischer’s messages with his former girlfriend were only “fantasy.”

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“All they did for their entire relationship was basically talk back and forth, crazy talk [and] they both smoked a lot of marijuana together,” Savage told The Daily Beast. “Just sort of unexpected behavior for children of that age.

“They’re children who are carrying out adult activity with juvenile minds,” Savage added.

When prosecutor Jennifer Shealy questioned Fischer about the elaborate tale about the rapist and the babysitter, one woman sitting with Fischer’s family covered her ears, the Charleston Post and Courier reported.

“Is what you’re telling the court that you lie, lie, lie, lie?” Shealy asked Fischer. The now 19-year-old replied, “About those particular things, yes.”

Still, it’s unclear why Fischer concocted such a violent story. Phone records in the criminal case reveal that Brown appeared to buy into Fischer’s tales.

Fischer described how the childhood tragedy continued to haunt him and went into gory details on how he’d seek “vengeance.”

“I remember her face. Pale. Scared. The blood. She fell on the floor. I guess he thought she died or something. I remember the noise the knife made. It’s not like what you hear on tv. It’s quieter but it’s a soothing sound. I liked it. But I hated it,” Fischer wrote.

Fischer said cops “busted down the door” after his sisters were raped, and that the babysitter survived the attack to dial 911.

“He was right, I didn’t remember it,” Fischer said, referring to the fictional attacker. “But I had that murderous urge.

“Then 13 years later, he wrote a note to me from prison. ‘I miss you and remember, your [sic] next.’ Then I remembered. I remembered every detail. And now he’s out.

“After 14 years, I’ll get my vengeance. He will suffer. I’ll make sure of that,” Fischer said, before describing a pattern of torture too gruesome to print but which culminated in, “I’ll hang him like a deer and gut him.”

Fischer then told Brown, “I’ve never told a single person this. It’s my deepest secret. If you think I’m some messed up kid bc of my thoughts of killing then oh well, I get it.

“Just don’t tell anyone,” he concluded.

Brown later replied, “I’m with you Matt. You’re not going through this alone.”

Then, a week before the stabbing, Fischer sent another text to Brown warning that he would hurt Cavanaugh if he had to.

Prosecutors introduced the messages at the “stand your ground” hearing and suggested they revealed Fischer’s possessiveness over Brown and his jealousy of her friendship with Cavanaugh.

“I know you don’t want me to hurt him, but he needs to go,” Fischer wrote.

The high school rivalry turned fatal on Jan. 18, 2015, after Cavanaugh messaged Brown on Snapchat while Fischer was hanging out at her home.

That day, Brown showed Fischer a pocket knife she got for Christmas from her father. The blade, which would eventually become the murder weapon, was in a case on her dresser, according to police reports.

In an interview with police, Fischer claimed that Brown gave him the knife as a gift and that he placed it in his pocket. The teenager claimed he only remembered he had the knife on him hours later, when Cavanaugh had him in a headlock and he couldn’t breathe.

“I’m not going to lie,” Fischer said, according to a transcript of his police interview. “He would have kicked my ass completely. So what happened was, I had a knife in my pocket, not knowing that I was going to have to—so I got it.”

He later added, “It was, like, in the heat of the moment. I honestly had no intention of doing that to him.”

Cavanaugh started messaging Brown in the afternoon.

Around 1:49 p.m., he wrote, “Wuddup buttercup. How are you and Matt doing?” court records show.

As the hours passed, both Brown and Fischer sent messages from their devices, trying to score weed, phone records reveal.

Brown was messaging someone in her phone named “suckhead00,” who agreed to meet her after work at 7 p.m. (Savage told The Daily Beast that Fischer and Brown were outside waiting for “suckhead,” not Cavanaugh, just before the stabbing.)

Eventually, at 5:21 p.m., Brown replied to Cavanaugh. “Sorry had to solve an argument,” she wrote.

When Cavanaugh asked what happened, Brown said she had a fight with Fischer. That’s when Fischer apparently grabbed the iPod and wrote, “It’s Matt please get out of our relationship. She doesn’t want you. So please shut the fuck up.”

“What the fuck? She’s my best friend you stupid inconsiderate prick. I have no interest in taking your girlfriend,” Cavanaugh replied.

“Honestly I’m sure you’re a really cool guy but you fucked things up for yourself. We were together for a week before you tried hooking up with her,” Fischer wrote.

Cavanaugh seemed to taunt Fischer, writing that if Fischer “weren’t such a little bitch,” Fischer would say all of this to his face. In response, Fischer warned, “If you wanna meet up, man, let’s meet up.

“Come to her house now,” Fischer added. “The only reason I don’t come to you is because we don’t have a car. I’ll fuckin kill you Lucas you don’t know me. Come here right now.”

Cavanaugh replied, “Sure thing man. I have no problem beating the shit out of you.”

Cavanaugh’s last message to Fischer was at 6:32 p.m.: “Cool. See you in a bit.”

It was 6:59 p.m. when Fischer first dialed his mother, while Cavanaugh lay mortally wounded in the street outside Brown’s home.

As The Daily Beast previously reported, the teenagers started fighting after Cavanaugh drove to Brown’s residence.

Brown originally told police in two separate statements that Cavanaugh started the fight, court records show. “When Lucas got here there were no words exchanged but Lucas came at Matt first,” Brown told police on Jan. 19. “During the fight I was yelling for Matt and Lucas to stop fighting.”

She added, “Lucas got the upper hand. He was kinda winning. They were up against the car. They were punching.”

Yet when Brown testified last week, she said Fischer ran up to Cavanaugh’s car and started banging on his window, Live 5 News reported.

She said she tried stopping Fischer from going outside to fight Cavanaugh. This was also reflected in a Jan. 22 statement to police. “Matt tried to leave my room, but I locked the door and blocked his path,” she said, adding that she “kept telling him to go back inside, and that nothing was going to happen and Lucas wasn’t going to show up.”

Fischer allegedly replied, “Oh yeah. He’s coming,” according to Brown’s interview with Mount Pleasant detectives.

But Fischer and Brown stood across the street from her house waiting. Fischer watched every vehicle that passed and asked if it was Lucas, Brown said.

Brown testified last week that Cavanaugh put Fischer in a “headlock” to subdue him. Eventually, Cavanaugh and Fischer faced each other.

“I saw Matt reach into his back left pocket and that’s when I remembered the knife,” Brown testified. “I screamed, ‘Stop, he has a knife.’ I saw his arm come to the front of his body and they backed up from each other.”

Cavanaugh lifted up his shirt and fell to the ground, Brown said. His insides were spilling out from his wounds, she testified.

Fischer dropped his knife and walked back into her home, while Brown’s mother rushed past him and kneeled at Cavanaugh’s side.

Brown would message Fischer a warning at 7:05 p.m., phone records show.

“Cop has a gun. More on the way. Stay off the roads,” Brown wrote.

Minutes later, she added, “Delete all messages. My mom told them your address. Don’t go home.”