Doug Martin Police Footage Released Following Mysterious Death

TMZ Sports has obtained footage from the night of Doug Martin's death ... showing the former NFL star acting erratically as he broke into a home before passing away in police custody.

The Oakland PD just released the 911 calls, body cam, and surveillance video of the October 18 incident.

In the first call, the homeowner said someone had broken into their home and asked responders to hurry. The caller stated this was the second time this happened.

As the first call came in, dispatch received another from Martin's mother ... who explained Doug had left his house on foot and was experiencing a mental-health emergency. She said Martin takes sleeping pills, but he hadn't slept for three days.

Police say Martin was initially unsuccessful when he tried to enter the residence -- when they got to the scene, they could see someone inside a home and instructed the individual to come out, but he did not comply.

Surveillance video shows Martin breaking through a fence and running into a backyard of a neighbor's home. Martin is seen yelling and busting a window as he entered the home as an alarm rang.

Officers followed, identified themselves and instructed Martin to put his hands up -- as a watch commander requested paramedics to come to the scene.

When cops got into the residence through the broken window, they tried to communicate with Martin, who was located inside a bathroom.

When he came out, a brief struggle ensued before officers were able to place him into custody ... with several cops asking him to calm down as they held him on the ground.

Eventually, they were able to get him in handcuffs ... and officers told Martin they were going to get him help. As he was in cuffs, an officer unholstered their taser -- but did not use it.

As they waited for paramedics, officers checked for a pulse and breathing. When the private paramedic company arrived, they were unable to get a gurney inside to Martin.

Once he was carried outside, It was then determined Martin had stopped breathing ... and officers removed the handcuffs so CPR could be initiated.

Martin was rushed to a nearby hospital ... where he was pronounced dead.

His death is still under investigation by the coroner's office. The incident is also under investigation by the Oakland PD's homicide section, internal affairs division, the Alameda County DA, and Oakland Community Police Review Agency.

The officers were involved were placed on administrative leave as part of departmental policy.

Martin's former agency -- Athletes First -- shared a statement on behalf of the family the Monday after he passed ... which explained how Martin's parents had contacted local authorities earlier in the night for "medical assistance."

"Feeling overwhelmed and disoriented, Doug fled his home during the night and entered a neighbor's residence two doors down, where he was taken into custody."