TMZ Sports has obtained police dispatch audio connected to Marshawn Kneeland 's death ... which reveals the Dallas Cowboys player told his family goodbye in an apparent mental health episode.

The clip is from late Wednesday night -- operators in Texas are heard relaying information from Kneeland's girlfriend, who stated she received a concerning message from the 24-year-old and was trying to contact the defensive end's agent. Getty

The girlfriend said Kneeland was armed and had a history of mental issues ... and she was quoted saying he would "end it all."

The dispatch also stated the NFL called Plano PD regarding one of its players ... stating the "subject is texting his family goodbye." Gallery Launch Gallery Getty

Dispatch then mentioned being on the phone with the Da

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