"The Voice" alum Ryan Whyte Maloney fatally shot himself in Las Vegas over a heated argument with his fiancée about her jacket, according to the police report.

Cops say the incident began in the early morning Tuesday when Maloney -- who was apparently drunk -- got into it with his fiancée in their car after leaving the New York-New York Hotel and Casino.

Per the report, the fiancée told police they were driving home when she peppered Ryan with questions about whether he had her jacket.

Police say Ryan got annoyed and called her a "bitch," before removing a handgun from the glove compartment and hopping out of the vehicle.

The fiancée told cops she heard a gunshot and rolled down her window to yell for Ryan, but he had already taken off on foot.

Cops say the fiancée heard a second shot as she ran after Ryan and watched his body collapse to the ground ... with a bullet wound to the head.

After the fiancée called 911, police officers raced to the scene and pronounced Ryan dead.

The report says the violence was captured on surveillance video from two casinos -- the MGM and New York-New York, from where he posted a video to his Instagram the night before his death.

Police say Ryan had previously contemplated suicide and had slash marks on his arms from harming himself.

Ryan competed on season six of "The Voice" in 2014 ... performing Journey's song "Lights" in a blind audition to earn a spot on Blake Shelton's team.

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