(CBS DETROIT) — Michigan Attorney General Dana Nessel sent a letter Tuesday to the Oxford Community Schools Board of Education, renewing an offer to conduct an independent investigation into the deadly shooting at Oxford High School.

Nessel requested the board to respond by May 20.

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The letter comes after Nessel met with families on Monday, which she said is the second of multiple forums she plans to host. She said despite different opinions, the community overall is seeking to learn more about what happened.

Click here to read the full letter.

“Under Michigan law, a board of education has the ultimate responsibility for school district operations. Among other things, the law gives each board the power to provide for the safety and welfare of students. This awesome authority has been placed in the hands of local boards to help ensure that the persons responsible for the critical operations of the school are also directly accountable to the communities they serve,” Nessel said in the letter. “To put it plainly, the families you serve want transparency and – as board members – you have an obligation to provide it.”

The attorney general previously offered to conduct a third-party review a week after the Nov. 30 shooting. However, the school district declined at that time.

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She said the cost of the investigation will be “borne solely by my office and the investigation will be conducted in such a manner as not to interfere with the ongoing criminal proceedings being handled by the Oakland County Prosecutor’s Office.”

Four students were killed in the shooting. Six others and a teacher were injured.

Ethan Crumbley, 15, who attended the high school, is facing multiple charges including murder and terrorism. A judge last month order for the teen to remain in the Oakland County Jail as opposed to going to the juvenile facility as requested by his defense team.

The teen’s parents, James and Jennifer Crumbley, are each charged with involuntary manslaughter. A judge denied a motion Tuesday to reduce their bonds.

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