The Metro Nashville Police Department released new findings on Monday about Audrey Hale, the assailant who fatally shot six people at an elementary school in Nashville, Tenn., last week.
In a press release, MNPD said the investigation so far suggests that Hale had planned the shooting for months.
"It is known that Hale considered the actions of other mass murderers," MNPD wrote in a press statement.
MNPD said the new details about the shooter came after reviewing several pieces of writings that were found in Hale's bedroom, as well as the assailant's car parked near the Covenant.
The department added that motive has not been determined and remains under investigation.
Ballistic reports also show that Hale fired a total of 152 rounds while in the building. Meanwhile, officer Rex Engelbert discharged a total of four rounds from his rifle and another four rounds from a pistol was discharged by officer Michael Collazo, MNPD said.
Hale killed three children and three adults at the Covenant School on March 27. The victims included Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all 9 years old; Cynthia Peak, 61, a substitute teacher; Mike Hill, 61, a custodian; and Katherine Koonce, 60, who served as the head of the school.
Hale, 28, was killed by police within minutes of the first call of an active shooter.