Inset: Ivan Vetecnik (GoFundMe). Background: Police in Salt Lake City, Utah, investigate Vetecnik's murder in 2021 (KSL).

A Utah teen is headed to prison for decades after he stabbed his friend more than 30 times, chopped up part of his body and dumped the remains in a cargo trailer.

Rowdy Lee Aguilar, now 21, was sentenced to between 25 years and life for the slaying of 15-year-old Ivan "Nik" Vetecnik in Salt Lake City. Aguilar pleaded guilty to aggravated murder with a mental health condition in September.

Vetecnik's sister Samantha VanTreese made a victim impact statement at Aguilar's sentencing last week and spoke directly to Aguilar.

"You were his friend," she said, according to local NBC affiliate KSL. "He trusted you. My brother looked up to you. And in return, you gave him terror, pain, and his last moments alone. I will never understand how a person could do something so cruel. I hope you think about the life you took — not in a vague or distant way, but specifically — him. His laugh. His innocence. His family. What you destroyed is not replaceable."

VanTreese said Aguilar also addressed the victim's family.

"He said, 'I just want the family to know that Nik did absolutely nothing to me. And I'm sorry for being a snake. I'm sorry for being a monster,'" VanTreese told the outlet.

As Law&Crime previously reported, Aguilar was 17 when he murdered Vetecnik on May 26, 2021.

Prosecutors said surveillance video showed the two buddies go into Aguilar's home around 10 a.m. on the day of the murder. More than three hours later, Aguilar walked out of the home alone with a blood-soaked shirt. He then went to a nearby business carrying garbage bags.

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Aguilar's father called police later that day when he found Vetecnik's body in the trailer, which "smelled strongly of cleaning agents," cops said.

Investigators recovered a bloody leather glove and a knife inside the trailer, along with the remains. Other body parts were recovered behind the home.

Aguilar initially denied even knowing Vetecnik and claimed he was at his girlfriend's house all day. He had cuts to his hands, which he claimed came from slicing ribs for a barbecue. The defendant eventually admitted to killing his friend, saying "I did it." Investigators never publicly revealed a motive for the attack.

Aguilar will remain at a youth facility until he is 25 before being moved to the adult prison, where he will serve the remainder of his sentence.

Vetecnik's sister Samantha VanTreese wrote in a Facebook post that the guilty plea felt like a win.

"But at the end of the day no amount of time in prison will ever be enough!" she wrote. "He took my baby brother in the worst way possible!"