Barrett was found unresponsive in a Sumpter Township mobile home park on New Year's Day, according to police.
Candice Renea Diaz, 24, the child's mother, as well as Diaz's boyfriend, 28-year-old Brad Edward Fields, are charged in an arrest warrant approved by the Wayne County Prosecutor's Office with murder, child abuse and torture, reports CBS Detroit. She was rushed to St. Joseph Mercy Hospital in Ann Arbor, where she was pronounced dead.
A postmortem uncovered signs of Battered Child Syndrome, denoting the girl had likely suffered egregious abuse for an extended period of time.
Diaz told cops Fields punched her and smashed her phone before turning the gun on himself and blowing a whole in his leg, shouting "see if you can outrun these bullets", according to the report.
Fields allegedly faked a gunshot wound on May 25, 2016 in an incident where he was accused of assaulting Diaz and possibly shooting her dog, police said. Child Protective Services and the Michigan State Police are assisting local detectives on the case.
Currently, US Marshals are offering a reward of up to $5000 leading to the arrest of Candice Diaz and Brad Fields.
He was later arrested on domestic violence charges.
In 2006, Fields pleaded guilty to carrying an unauthorized concealed weapon and served a year of probation.
No one from CPS was immediately available for comment. The second page makes clear that donations will be used by Gabby's father, Kyle Barrett, to lay his daughter to rest.
"She didn't have to pass the way she did, but I hope we get justice for her really soon", Barrett said.
"She was an overall incredible kid".
"She's just a little angel".
Donations were being accepted by Gabrielle's family at a Go Fund Me page.