An 18-year-old man in Florida has been arrested for allegedly killing his 81-year-old roommate, stabbing the victim more than 100 times over the weekend and reportedly telling authorities it was because the elderly man was “already dying.”

Moses Ojeda was taken into custody on Sunday and charged with one count of first-degree murder and one count of tampering with evidence for the slaying of Patrick Benway, who authorities say suffered a total of 113 stab wounds.

“This was a senseless and tragic act of violence. Our detectives, forensic investigators, and Bartow Police Department officers worked diligently to take Ojeda into custody and gather evidence to hold him accountable,” Polk County Sheriff Grady Judd said in a statement.

According to a news release from the sheriff’s office, Benway and Ojeda were living in a “group home” on Blue Bird Avenue with three other roommates. The home was being managed by “ET Home Care, LLC,” and Ojeda had only moved into the home one day prior to the stabbing after being released from a local hospital.

When detectives on the scene interviewed Ojeda, he allegedly told them he “did not have any problems with the victim and described him as a good person,” the sheriff’s office wrote.

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Ojeda confirmed to police that he entered Benway’s bedroom, where he was lying in bed and stabbed him multiple times, cops said. The victim did not physically resist but did ask, according to Ojeda, “Why would you want to do this to me?” before succumbing to his injuries, police said.

“Ojeda stated he has no regrets and he wanted to kill him because he was ‘already dying,’” according to the police statement.

Ojeda told deputies that after fatally stabbing Benway, he cleaned the murder weapon before putting it back in the kitchen. He then allegedly took off his “blood-stained clothing” and put them in his laundry basket.

“Moses said that he went to the victim’s bathroom where he washed the knife and cleaned it up, where he washed the blood off himself. He then replaced the knife in the butcher block where it was originally placed out of sight,” Judd said during a Monday news conference.

Detectives said all of the physical evidence gathered at the scene was consistent with the story told by Ojeda.

Judd speculated that Ojeda’s criminal defense attorney would claim that Ojeda was not in his right mind at the time of the murder, but said the defendant’s actions showed he knew what he was doing when he allegedly killed Benway.

“It’s a no-brainer that the defense is going to be that of insanity but I’m telling you, he had clear criminal intent. He acted with malice, with forethought and then he went through the effort to hide the weapon,” the sheriff said.

Adrena Thornton, the landlord of the home, was in tears when she discussed Benway with Spectrum News.

“It’s like the devil showed up at the door and rocked everybody’s world and took an innocent man’s life,” she said. “He was very happy with where he was at. My mama had just talked to him the day before and he was just, he was just real happy.”