Representatives of the mother, sister, and estate administrator of Tamir Rice, the 12-year-old boy whom Cleveland police officers shot and killed in November 2014, wrote to the Department of Justice today formally requesting that the federal government intervene to investigate both the boy’s death and local prosecutor Timothy McGinty’s handling of the case.

For months, the Rice family and their representatives have expressed growing concern about unfairness and bias in the grand-jury process. Evidence of that bias and unfairness became so extreme that the family in October 2015 called for recusal of Mr. McGinty and appointment of an independent prosecutor.

Last week, on December 7, 2015, the prosecutor’s misconduct intensified even further.

Because it was apparent that the presentation to the grand jury was so unfair, the family was forced to retain its own experts in an attempt to have the grand jury consider accurate information on what actually happened the day Tamir Rice was killed. Although local prosecutors promised they would present those experts to the grand jury in a fair manner, in a remarkable turn of events, they sabotaged testimony of the family’s experts through a series of highly unprofessional and inappropriate tactics before the grand jury.

The family’s two experts, Jeff Noble and Roger Clark, nationally recognized figures in the fields of law enforcement and excessive-force policy, left the grand jury last week stating that in their many decades of experience in state and federal courts across the country, they had never encountered such unfair, biased, unprofessional, and hostile treatment by a prosecutor’s office.

This duplicitous mistreatment of the family’s experts stands in stark contrast to the favorable treatment afforded the officers who killed Tamir Rice when they were allowed to read self-serving, prepared statements to the grand jury, without ever being cross-examined, even though the law is clear that by taking the stand to read their statements, the officers waived their Fifth Amendment privilege to be silent.

This latest act of prosecutorial misconduct provides further evidence that the grand jury process has been irreparably harmed in this very important case. It is clear local prosecutors are doing everything in their power to exonerate the officers, no matter what the evidence shows. They are not engaged in the transparent, fair, and thorough investigation of the truth that they promised Tamir Rice’s family, the citizens of Cleveland, and the nation, ensuring that the officers will never face justice.