BAILEY, Colo. -- State and county authorities held a news conference Wednesday afternoon to update the public on their investigation into the Sept. 27 standoff and shooting at Platte Canyon High School.

The Park County Sheriff, District Attorney and CBI Division Director talked about the general status of the investigation, including a timeline that has been developed, but took no questions. They said they could not discuss specifics of the case because it is still under investigation.

Authorities earlier said 53-year-old drifter Duane Morrison took six girls hostage at the high school. He then released four of them before killing Emily Keyes and himself when a SWAT team stormed the classroom.

"CBI's laboratory has examined items related to Emily's cause of death," said Steve Johnson, the Div. Director for CBI investigations. "The evidence leads us to the conclusion that the single gunshot wound that Emily sustained was caused by Morrison."

The timeline revealed that Morrison entered and left the school parking lots a number of times the morning of the shooting. A school security camera captured images of Morrison's distinctive jeep.

Johnson released the following timeline:

8:42 a.m. Morrison's Jeep arrives in the upper administration parking lot
8:44 a.m. Morrison's Jeep leaves
8:46 and 8:48 a.m. Morrison's Jeep was seen parked in student lot in the space it was later found
8:57 a.m. Morrison's Jeep was gone from space
9:44 a.m. The Jeep was back in student lot
10:53 a.m. Morrison seen exiting Jeep
11:40:59 a.m. First call from school to Park County Sheriff's Office
11:43:28 a.m. First Park County Sheriff Deputy arrives at school

Johnson also said Morrison's Jeep was spotted in the upper administration parking lot the day before the shooting, arriving at 11:32 a.m. The Jeep left at noon, he said.

"We are also reviewing other footage form the video camera to see if Morrison was at the school," said Johnson.

Investigators are still trying to find out what led Morrison to pick Platte Canyon High School and the girls he took hostage.

"After, listening to Dr. Elliot, he's as baffled as I am. So far it sounds pretty random," said Park County Sheriff Fred Wegener. "It's just a sad event."

Dr. Delbert Elliot is an expert on school violence at the Center for Prevention of Violence who Wegener has been consulting throughout the investigation.

Morrison's suicide note has been sent to the FBI for behavioral analysis.

Investigators in Colorado are looking in to the Amish school shooting in Pennsylvania, although they wouldn't say why.

Investigators have conducted 124 interviews and collected 178 items related to the case.

Security has been increased at the high school. All of the doors remained locked except for one. The school wants to add more security cameras. Wegener said he also wants to have a guard or two, however, he said that is not in the budget at the moment.

Wegener thanked all first responders who went to the school the day of the standoff and shooting.

"Now is the time to put plans in place to make sure this doesn't happen again," said Wegener. "Our community will rebuild."