WILLMAR, Minn. - A Willmar teen who once wrote about his grandmother being his hero will serve at least 30 years in prison after admitting to his involvement in her murder.

Robert Warwick, age 18, received a life sentence in Kandiyohi County Court Wednesday morning after pleading guilty to first degree murder in commission of a felony, which was the burglary of his grandmother's home. In exchange for the plea prosecutors dropped a charge of first degree premeditated murder, which would have meant life in prison with no parole.

Lila Warwick was found dead in her Willmar-area home in late July of 2013. Investigators soon arrested Warwick, his friend Brok Junkermeier and another teen for her murder. The 79-year-old was beaten and stabbed multiple times as the teens attempted to rob her of what they believed was tens of thousands of dollars stashed in her home. Police say Robert Warwick was the mastermind of the crime, while Junkermeier was the one who carried out the killing.

Junkermeier earlier pled guilty to first degree premeditated murder. He will never be released from prison.

In court Wednesday Robert Warwick apologized to his family members. "I'm really sorry... I wish I could take back my actions," he said. "I hope some day everyone will forgive me."

In victim impact statements Warwick's aunt Cheri Eckbom, Lila Warwick's daughter, said she believed she could forgive Robert, but wasn't about to let him forget about the savagery of his crime. "She referenced a paper found on Lila Warwick's desk that was written by her grandson, in which he called her his hero.

"Whatever happened to that sweet young man that thought his grandma was his hero?", Eckbom asked as Robert Warwick wiped tears from his eyes with a sleeve. ""I hate the evil thing you did but I love you... and your grandma loved you."

Warwick continues to maintain that he intended to rob his grandma but not kill her, something the teen repeated in court Wednesday.

"Brok told me it wouldn't happen... but it happened," Warwick told a packed courtroom.