Ne-Yo -- FBI Contacted Over Death Threats

A man who allegedly threatened to shoot Ne-Yo in the head was detained for a psychiatric evaluation in L.A. ... and top ranking execs at Sony Music believe they are also on the hit list.

Sony Music Entertainment has just obtained a temporary restraining order against Jeff Choi -- who allegedly has been making deranged, escalating threats for months ... because he believes the music company released several songs ABOUT HIM without permission.

Sony claims Choi sent hundreds of threatening emails, made dozens of angry phone calls and even went down to the Sony offices in person to complain ... but was escorted out of the building after he became belligerent.

According to court docs, Choi believes Ne-Yo, Sony honcho Clive Davis and Sony CFO Kevin Kelleher are all to blame ... and he's made threats to "shoot people in the head" unless Sony pays him $800,000.

Sony security contacted the FBI -- which conducted its own investigation and decided to detain Choi for a psychiatric evaluation in August. He was eventually taken to a mental health facility, where he he continued to phone in threats to Sony execs. The FBI and federal prosecutors have now decided to prosecute Choi for making the threats.

Sony then filed for the restraining order against Choi -- fearing he will make good on his threats when/if he is released from custody.

An L.A. County Superior Court judge granted the request -- temporarily banning Choi from going near the Sony offices and requiring him to stay 100 yards away from Davis and Kelleher.