The newspaper’s Magazine took a deep dive into the May 2015 crash in Philly. Here’s the TL;DR version of what you missed.

Nine months after Amtrak 188 derailed in Northeast Philadelphia, the cause of the crash that killed eight people and injured dozens more remains a mystery.

This morning, the New York Times Magazine published a story from writer Matthew Shaer that dives deep into the May 2015 crash, offering the most detailed portrait yet of what happened in the events leading up to the crash and, importantly, the state of mind of the train’s engineer.

It also offers up a number of theories for what might have happened. Sure, speed was a factor; we already knew engineer Brandon Bostian navigated the train around a bend at more than double the posted speed limit. But unfortunately for investigators trying simply to figure out “why,” there still seems to be no smoking gun. Bostian wasn’t texting or fiddling with his phone. He wasn’t drinking beforehand. And those who know him say he was way too conscientious to have purposely screwed something up.

Here are six things we learned today about the investigation process and what might have sent Amtrak 188 flying off the rails at the Frankford Junction:

1. ‘Lost situational awareness’ is probably the cause

While investigators with the NTSB refuse to go on record about causes of the crash, Shaer reports the key is likely something investigators call “lost situational awareness.” And from there, it seems there are two schools of thought as to what happened.

One investigator speculates that a projectile hit the windshield — as it had other trains in the area that night — and Bostian instinctively ducked, hitting his head on the dashboard and knocking himself out. Bostian has said through his attorney that he has no memory of what happened that night or what might have caused the crash.

The second theory is more rooted in the idea of what’s referred to when driving cars as “highway hypnosis.” It can happen to train engineers too who are lost in the endless tracks ahead of them and get confused as to which curve they’re entering. It’s possible Bostian was tired, and confused Frankford Junction with the curve that comes ahead of it. When he realized his mistake, he could have inadvertently speeded up, and sent the train flying off the rails.

2. This is more of a mystery than most

For most incidents the NTSB investigates, there’s some sort of smoking gun. There’s an indication of a mechanical failure or a clear human error. There’s data from a black box that shows something went wrong with the engine. Something.

But that hasn’t happened in this case. According to Shaer: “Faulty signal boxes were dismissed as a possible contributing factor, as were track anomalies and major problems with the locomotive: Data from the black box showed the engine was working perfectly well right up to the moment of derailment. Computer glitches have also been ruled out.”

3. Bostian was ‘frazzled’ that night

Engineers who operated Northeast Corridor trains for Amtrak had a tough spring, as their break times had been cut despite objections from their union. In some cases, they went from two hours to 90 minutes or less.

The day of the crash, Bostian encountered problems with his cab signals after departing from New York, meaning he had to cap his speed at a lower level than usual so he could look at manual signals along the rail. That put him 30 minutes late heading into Washington, D.C.

His break time was gone. And a colleague at Amtrak told The Times that he seemed “frazzled” at Union Station before heading into Philly.

4. Pressure on engineers is high

Investigators have said that if Positive Train Control technology had been installed on this part of the Northeast Corridor, the crash of Amtrak 188 could have probably been prevented.

The technology installed on rails automatically slows trains that are moving too quickly, and despite pressure from the feds, Amtrak had failed to install it along the Frankford Junction portion of the Northeast Corridor. Since then, it’s been put in.

Not helping things: The lack of the auto-braking system called Positive Train Control, or PTC, clearly puts a lot of pressure on engineers who are, without it, forced to perform everything perfectly.

“I’ll describe it to you this way,” Sarah Feinberg of the Federal Railroad Administration told The Times. “If a train is traveling in an area where PTC isn’t in place and working as a backstop, you’ve got a situation where an engineer has to execute everything perfectly every hour, every day, every week. All the time. Because the slightest, smallest lapse can mean disaster.”

5. Bostian was obsessed with his job

The crash was a shock to people who knew Bostian. His friends and colleagues told The Times that he never grew out of a childhood love for trains, often spending his evenings off on message boards and forums discussing technology, changes to engineering and crashes that had recently occurred.

As Shaer wrote: “Bostian seemed far too conscientious to have deliberately taken his attention from the controls — no one I spoke to, official or colleague, would give any credence to the proposition that the accident was intentional.” Depending on what investigators find, Bostian could face criminal charges in connection with the crash.

But perhaps the most tragic revelation of The Times‘ story was this though that came from a college friend of Bostian’s: “When I heard about the accident, my first thought was, I wish Brandon was driving that train, because it never would have crashed.”

6. We’ll know more next week

Shaer reports that the National Transportation Safety Board, the federal agency investigating the derailment that was one of the largest in decades, will release a preliminary report of its investigation within the first week of February.

But while that report is expected to include “raw data from the train’s black box, imagery from the site and notes from investigators,” it probably won’t draw a conclusion on a cause. That should come by spring.