A cause of death was not given.
"Early this morning our families lost a phenomenal human being. Aaron Cox was a tremendous son, brother, and brother-in-law. He had a deep love for his family, and a passionate dedication and commitment to his friends. As our families grieve together, we will also celebrate the memories, the laughter, and the love we each shared with Aaron in the short time we had him," Trout, his wife, Jessica, and their families said in a statement.
"He will forever be at the forefront in the hearts and minds of the Cox and Trout families. We will rely on the love and strength of God first and foremost during this difficult and challenging time, as well as our dear family and friends. We thank you for your thoughts and prayers, and our Lord and Savior for His precious gift of Aaron Joseph."
Cox was Jessica Trout's brother.
The 24-year-old right-handed reliever had pitched the past three seasons in the Angels' system. He made 11 appearances for the Angels' High A team at Inland Empire this season, going 0-1 with a 4.11 ERA, but retired from baseball on Aug. 6. He had a career record of 7-3 with a 3.64 ERA in 68 appearances.
"The Angels Organization is saddened to hear of the passing of Aaron Cox, a member of the Angels family since 2015. We are deeply heartbroken and shocked by this tragic loss. Our heartfelt prayers and condolences to his family and friends. Aaron will always have a special place in the hearts of those within the organization," the team said in a statement.
Cox was suspended 50 games last season for testing positive for Ritalin, which is a banned stimulant in Major League Baseball. Players can take the drug only if they receive a therapeutic use exemption.
The Angels had announced earlier this week that Trout was away from the club for a family matter and might not be available Thursday, when he is scheduled to come off the disabled list.
Trout was put on the 10-day disabled list on Friday because of an inflamed right wrist, a move that was retroactive to Aug. 6, when Trout received a cortisone injection in his wrist. Trout hasn't played since Aug. 1, when he hurt his wrist during a feet-first slide into third base in Tampa Bay.