NFL quarterback breaks silence on brother's murder

San Francisco 49ers quarterback C.J. Beathard says he's heartbroken after the murder of his younger brother, but says he's finding "some peace knowing that he is at peace in heaven."

Clayton Beathard, 22, and Paul Trapeni III, 21, were stabbed to death outside a Nashville bar in the early hours of Dec. 21.

Trapeni was a student at Rhodes College in Memphis, while Clayton Beathard was a junior at New York's Long Island University, where he played quarterback on its football team.

C.J. Beathard, 26, is opening up about his relationship with his little brother, saying he had "the biggest heart of anyone that I have ever known."

"He is the most loyal guy that I have ever known in my life and has always been so dang proud of my family and I," Beathard wrote on Instagram Friday. "It sounds so cliche but clay is the best example of a dude that lights up every room he walks into wether [sic] its with his loud contagious laugh or just the smile on his face.

"He also has the weirdest ways of making unforgettable relationships with literally everyone he meets," Beathard added. "Clay is the sweetest, most humble, toughest, and kind hearted people this world had in it, but he was called home and now has none of the pains and stresses only this world could give."

C.J. Beathard, a backup signal caller for the 49ers, described coming to terms with his brother's death.

"I just know Clay is looking at us grieving down here right now saying 'stay strong' 'I'm doing great up here' and 'I will see you soon,'" Beathard said. "What happened is absolutely awful and has been and will continue to be the hardest things my family and I have had to go through. But I can find some peace knowing that he is at peace in heaven right now, and I know without a doubt God will bring a whole bunch of good out of this."

"My relationship with God has strengthened so much already throughout this along with my family's. I have come to see a whole new view on life, in such a good way," Beathard said.

He ended his post by urging others "to make sure you tell everyone you love that you love them as much as you can, because you have absolutely no idea when the last time you may talk to or see them again will be."

The prime suspect in the stabbings, Michael Mosley, 23, was captured Wednesday at a vacant home in Ashland City, Tennessee, following a days-long manhunt.

Mosley's attorney, Justin Johnson, says his client acted in self defense, reported The Tennessean.

He's set to appear in court on Jan. 7.

Clayton Beathard's father, Casey Beathard, told ABC News on Friday: "We are thankful that [Mosley] is off of the streets. We are sad because two incredible young men are missed."

ABC News' Bill Hutchinson contributed to this report.