DETAILED sketches were found along with a chilling manifesto belonging to Covenant School shooter Audrey Hale after six people were gunned down at the Nashville school.
Police said they are reviewing the items and working on a theory into a possible motive behind the senseless massacre.
Hale, 28, reportedly drew a detailed map of the school, including several entry points, and even did surveillance in the area before killing three students and three adults.
Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all nine years old, died in the horrific rampage.
The adult victims were identified as Cynthia Peak, Mike Hill, 61, and Katherine Koonce, 60.
Koonce was the head of The Covenant School, according to .
Investigators have said that Peak was a substitute teacher and Hill was a custodian.
Hallie Scruggs was the daughter of Chad Scruggs, the pastor at Covenant Presbyterian Church in Nashville.
Hale, who was killed by police, is believed to have been a former student at the school.
Hale was armed with two "assault-style" weapons - a rifle and a pistol - along with a handgun.
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At least two of the guns were bought legally in the Nashville area, said police.
Metropolitan Nashville Police Chief John Drake said he was "literally moved to tears to see this and the kids as they were being ushered out of the building."
MAPS OF SCHOOL FOUND
Writings and a possible "manifesto" recovered from Hale revealed that the attack was calculated and planned, cops said.
A search of the shooter's home turned up a sawed-off shotgun, second shotgun, and other evidence.
"We have some writings that we’re going over that pertain to this date, the actual incident," Drake said.
"We have a map drawn out of how this was all going to take place."
Drake also told reporters that the school was breached when the shooter shot through a side door in order to enter the school.
Photos of a door with the glass shot out were shared on social media by police.
"Hale entered the Covenant building after shooting out the glass of these doors," wrote the MNPD.
Another location was reportedly mentioned in Hale's maps and manifesto, cops said.
However, the shooter ruled out this location because it had "too much security."
Cops released video that shows Hale stalking the school building as they continue to look into the motive behind the rampage.
So far, law enforcement has a "theory" they are investigating.
"There’s some belief that there was some resentment for having to go to that school,” Chief Drake told .
“Don’t have all the details to that just yet and that’s why this incident occurred.”
President Joe Biden called the shooting a "family's worst nightmare" while speaking at an unrelated event at the White House.
He called on Congress to pass a ban on certain semi-automatic weapons.
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"It’s ripping at the soul of this nation, ripping at the very soul of this nation," he said.