Gynnya McMillen was a fun and vivacious girl at just 16 years old. She also had come from a troubled home, including going from group home to group home. Relations between her and her mother, who would see here only sparingly as time went on, were especially raw in early 2016.

In a disturbing 911 call, McMillen's mother can be heard berating her and vowing to send her away.

McMillen's last days were spent not with other teenage friends or even with a foster family: They were spent in a cold jail cell abandoned and left alone for long periods of time at the Lincoln Village Juvenile Detention Center in Elizabethtown, Kentucky.

The initial police narrative of her death -- that she inexplicably died in her sleep in a juvenile detention center -- was quickly disproved when basic facts from an investigation began to come to light.

McMillen was brought into jail January 2016 after officers responded to a domestic dispute call to her home. She had gotten into it with family and someone made the decision to involve the law. Once she was brought into the detention center, she refused to take off her sweat shirt for a booking photo.

That's when things got physical between her and the guards.

She died in the grasp of jailers after being brought to the ground by jailers using what is called an "aikido restraint" -- a martial arts technique, according to CBS News. While there are many "aikido restraints" -- the particular one used has never been disclosed -- she was held in that position an inexcusable four minutes and 15 seconds, as jailers patted her down.

"The staff performed an Aikido restraint hold to safely conduct a pat-down search and remove the youth's hoodie," Lincoln Village Juvenile Detention Center spokeswoman Stacy Floden told CBS in an email response. "The purpose of having multiple staff involved in a controlled restraint is to ensure the safety of the youth and staff."

"As far as I'm concerned that is a completely inappropriate use of a restraint," Michele Deitch, an attorney and juvenile justice expert, told CBS. "This goes back to not being so punitive with kids. That's not just how you interact if you want to achieve a positive social response."

In the tussle, McMillen went down behind a counter, a crucial position that was obscured by the primary surveillance camera. Incredibly, a second camera that was in operation that day was somehow broken a week after the incident, according to police. What made matters worse was that jailers didn't begin CPR until 11 minutes had elapsed and McMillen had long stopped moving.

A 911 call (posted below) shows that a dispatcher asked if CPR had begun. The jailer said she "was new" and didn't know about CPR protocols. “I can find out. I don't know,” she can be heard saying. She also said, "The patient here is unresponsive. She is cold ... and there are no vital signs."

After the altercation with jailers, McMillen did not respond to several verbal commands, including those ordering her to get her plate of food. After a number of hours, she was found curled up in the fetal position. Dead.

A preliminary probe found no signs of a drug overdose or trauma, but the teen's family continued to push for answers. 

Then the Kentucky State Medical Examiner ruled that McMillen died from a rare genetic disorder that caused an irregular heartbeat. The family swatted the report down, determined to find the truth about their daughter.

Finally, in March 2016, speaking to reporters, Investigators ruled out "trauma or external injury" as a cause of death but found "a pattern of employee misconduct" among the jailers.

Just recently, after Kentucky Justice and Public Safety Cabinet Secretary John Tilley vowed earlier this year that nearly 60 hours of video surveillance footage would be released to McMillen's family, the truth has come to light. In its totality, the footage is a damning document against law enforcement.

Jailers repeatedly lied about checking on McMillen while she was in her cell, even when she was seen lying in the same position for 10 hours.

In August 2016, a lawsuit was filed against the state Department of Juvenile Justice and Lincoln employees for McMillen's death, according to WDRB.

The suit alleges that one guard in particular, Reginald Windham, who is facing charges for allegedly lying about checking on McMillen, "did not lift a finger to help her, instead returning to his desk," the suit says.