NASHVILLE, Tenn. (WKRN) — The lead investigator for the Covenant School shooting has urged a judge not to release a number of records in the case, saying the criminal investigation is still active and ongoing.

According to Metro Nashville Police Lt. Brent Gibson, who is overseeing the case, it will likely take a year to complete the investigation.

Six people, including three children, were shot and killed by 28-year-old Audrey Hale at The Covenant School in Green Hills on March 27. The victims were identified as Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all 9 years old; as well as Cynthia Peak, 61; Dr. Katherine Koonce, 60; and Mike Hill, 61.

Between meeting with and grieving with the victims’ families, interviewing witnesses, and gathering documents, Gibson said the criminal investigation hasn’t stopped since March 27.

However, authorities are still in the process of collecting and reviewing a number of records, including the shooter’s phone, social media, bank account, and gun and ammunition account records; autopsy and toxicology reports; and medical records, according to Gibson.

In court documents, Gibson said police need to interview the individuals identified in the records and investigate Hale’s actions in the months before the shooting.

Gibson also said law enforcement still needs to review Hale’s messaging data and internet search histories, which is often a time-consuming process, but it is used to determine whether the assailant had any help planning the shooting or purchasing weapons.

The document went on to say that even though the shooter died at the school, the criminal investigative file would not instantly close because authorities need to keep gathering and analyzing evidence “to determine if related crimes were committed, are being planned, or whether other people were involved.”

“While we believe at this time that the assailant acted alone in this case, we do not know for sure,” Gibson said, adding that the matter must be investigated thoroughly to rule out potential co-conspirators or other connected crimes.

According to the lieutenant, “harmful and irreversible consequences could result from disclosing investigative files prematurely” and “releasing any of the puzzle pieces too quickly could jeopardize putting this intricate puzzle together.”

Several lawsuits have been filed against Metro Nashville — most recently by The Tennessean and state Sen. Todd Gardenhire (R-Chattanooga) — calling for MNPD to release a number of records from the case, including the shooter’s journals and suicide note, and submitting that there is no pending criminal investigation or suspect to investigate.

The complaint said the shooting has caused a broader public debate regarding Hale’s motivations, goals, planning, and acquisition of firearms while under mental health treatment. The paperwork points to the records contributing to the gun control discussion, which is anticipated in the August special session of the Tennessee General Assembly.

Earlier this week, parents from The Covenant School collectively said they do not want Hale’s writings released to the public.

A hearing on the matter is set for Monday, May 22.