MYSERY: No Sucide Note From LEE THOMPSON YOUNG (RIP)

Lee Thompson Young's suicide is a dark mystery ... because law enforcement sources said that he did NOT leave a suicide note.

Young were found dead in his North Hollywood apartment Monday. He died from a self-inflicted gunshot wound.

Our sources say Young did have a diary ... but none of the entries reveal why he would have taken his life ... at least at first glance.

Young were last seen on Saturday and believe he may have taken his life sometime that day.

The case is a real mystery because everyone we've spoken with in Young's life tells us he had no apparent serious life issues.

Source: TMZ