The MSU police press release contains a timeline of the shooting.
It says the shooter left the student Union a minute before officers arrived.
A note attached to the release details 43-year-old Anthony McRae's plans to carry out the shooting.
It says, "I've been hurt" and contains disturbing language and images.
The note asserts McRae was working with a group 20 others who also planned to commit acts of violence.
Investigators say this claim is "unfounded" and that McRae acted alone and did not collaborate with other individuals.
Police say Ingham County 911 received over 2,000 phone calls on the night of the shooting.
They add the investigation into the incident is ongoing.