Shortly after midnight - Michael Hennen closes up Hennen's Restaurant after working a full shift; Hannah Barnes also worked at the restaurant that night.
2:40 a.m. - The pair stops at the Walmart on Signal Mountain Boulevard, where Barnes purchases a swimsuit.
Between 3 a.m. and 4 a.m. - Pair buys snacks and water at the Kangaroo gas station near Bakewell, Tenn.
3:57 a.m. - Michael Hennen texts the caretaker at the McDonald Farm in Sale Creek to say that he and a friend are going for a swim on the property that night. The farm is about 30 miles from Chattanooga.
6:10 a.m. - A Norfolk Southern train crew calls 911, reporting that the train has struck two people on the tracks crossing the property at the McDonald Farm.
Source: Hamilton County Sheriff's Office
While describing the deaths of a man and woman hit by a train as "just a tragic accident," Hamilton County Sheriff Jim Hammond said some details of what happened may never be known.
With speculation and rumors swelling in the wake of the Aug. 22 incident, Hammond said Wednesday no one may ever know what led the pair to the train tracks, why they lay on the tracks and embraced or why they didn't get out of the train's path.
But during a news conference, Hammond firmly emphasized investigators' conclusion that their deaths were an accident, and not suicide or foul play.
"There are no other circumstances that would lead us to believe that anything else occurred in these deaths," he said at the conference. "The medical report shows both parties were alive when struck by the train and that they probably did not see or hear the train coming. They may very well have fallen asleep.
"I don't know if we will ever know the full story."
Hannah Barnes, 19, and Michael Hennen, who would have turned 28 on Tuesday, were laid to rest last week. Hennen was manager at the family-owned Hennen's Restaurant, where Barnes worked as a hostess and waitress.
Hammond said the investigation is still open pending toxicology results, which will take two to four weeks to process at the Tennessee Bureau of Investigation.
On Monday, representatives from Norfolk Southern railway met with officials from the Hamilton County Medical Examiner's Office and the sheriff's office -- the only law enforcement agency investigating the case -- to review evidence from the train company.
The evidence included video recorded from a camera at the front of the train that records the train engineer's view of the tracks, explained Susan Terpay, director of public relations for Norfolk Southern. When processed, the video shows photos taken at a rate of four per second, she said.
Hammond said the images were grainy, black-and-white photos that show two people lying on the tracks in an embrace. The pair were lying on a railroad crossing where asphalt filled in the inner section of the tracks, making a flat spot, he said. Though the images were very poor quality, Hammond said they were clear enough to determine the two were fully clothed.
The shots show that they never broke their embrace or got up when the train was barreling down on them, he said.
"There does not appear to be any movement at any point in the sequence of shots," Hammond said. "There's no sign they recognized the oncoming train."
Norfolk Southern owns the exclusive rights to the photos, and the sheriff's office will not retain a copy of the video, Hammond said.
Terpay said the company will keep the photos on file indefinitely. Norfolk Southern's own investigation also concluded the deaths were an accident.
Information pulled from the train's event recorder, which functions like an airplane's "black box," shows that the 12-car train was rolling at about 45 miles per hour, Hammond said. The engineer had three to five seconds from the moment he saw the pair on the tracks before he hit them, Hammond said.
They were killed instantly, he said. Barnes was thrown from the tracks while Hennen was dragged under the locomotive for several yards, he said.
According to the Hamilton County medical examiner's reports released Wednesday, both died from "multiple blunt force injuries."
"They did not make any apparent effort to move and were possibly asleep. No indication of foul play. No suicidal intent known. Apparent accidental death," the notes on both medical examiner reports read.
Terpay would not release information on the train's crew. She said the company offers counseling and time off for crews involved in accidents.
"This type of incident can be very traumatizing for a train crew," she said.
Hammond said investigators believe the train crew did everything in their power to give warning and stop the train.
Hennen was the son of Tim and Corinne McDonald Hennen, who own Hennen's Restaurant. Tim Hennen also was a co-founder of Big River Grille in downtown Chattanooga.
Michael Hennen was the great-grandson of Roy McDonald, who founded the Chattanooga Free Press, and grandson of Frank McDonald, who was chairman and president of the paper from 1969 to 2000.
Barnes was the granddaughter of Marion Barnes, president of Covenant College from 1965 to 1978.
The Sale Creek farm where they were killed, known as McDonald Farm, has been owned by the McDonald family for decades.
Throughout the news conference, Hammond referred to Barnes and Hennen as "a young man" and "a young woman," never calling them by name.
Until Wednesday, nine days after the incident, the sheriff's office had not officially released the names of Barnes and Hennen.
A woman who answered the phone at the Hennen residence Wednesday declined comment on behalf of the family.
"The family appreciates the outpouring of support but would appreciate privacy at this time," said the woman, who did not identify herself.
Barnes' parents did not return messages for comment Wednesday.
Many details are unclear about what happened between the time the restaurant closed and Hennen and Barnes left, and when they died about 6 a.m. Monday, but the sheriff's office has established a basic outline of the pair's trip to the farm that night.
Hennen left the restaurant around midnight, investigators said, and at some point, he and Barnes headed to the farm in Hennen's car.
Hammond said investigators have not been able to determine whether there was a romantic relationship between the two.
"I can only tell you they were co-workers. At this point, there's no evidence that points to them being an item," he said.
Surveillance footage shows the two stopped at the Walmart on Signal Mountain Road about 2:40 a.m., where Barnes picked up a swimsuit. They then headed north toward Sale Creek, stopping at a Kangaroo Express gas station near Bakewell to buy snacks.
Close to 4 a.m., Hennen texted the caretaker of the farm to say he was there for a swim. But there's no evidence that the two actually swam, Hammond said.
At some point, the two went down to the railroad crossing, paved so the family could get farm equipment from one side of the property to the other.
Investigators found two cans of beer near the tracks, which they said came from a cooler near the house.
The account Hammond gave closely matches one written by commentator Roy Exum and published Monday on the Chattanoogan.com website.
Exum, a relative of Hennen's, had written that many in the family liked to go to the farm to swim in the pool and added that the access point on the railway was away from all security lights, a spot where many stars were visible.
Hammond noted that Exum's labeling of the incident as a "colossal accident and senseless tragedy" was well-put. The sheriff emphasized, though, that no explanation justified Hennen and Barnes' apparent decision to settle themselves down in the tracks.
"Of all places, this is not the place to lay if they are looking at stars, or whatever. Railroad tracks are very, very dangerous."