You're driving home in the rain. A deer jumps out and you managed to hit the brakes but still hit it, albeit having slow down to 10km or less. Slow enough that the deer is able to get up and runaway, but still enough to dent your car and crack a windshield. Any blood or hair gets washed away in the rain. Car runs well enough to get you home.

10 min behind you there is a hit and run and pedestrian is killed by a vehicle that drives off. No camera footage, no solid proof of who did it.

Eventually you come to a big intersection where there is a camera and it records your dented, cracked car rolling through 20-30 min after they estimate the pedestrian got hit. Ruh roh.

So you get charged with hit and run and manslaughter. There isn't a ton of ways to prove it's not you, even though it's clearly not. So your options are plead Guilty and get fucked, or roll the dice with Not Guilty, probably lose, and get fucked extra hard.

Alfred plea is basically hey I can't prove it but I also won't admit guilt. Prosecutors know they can't prove, specifically, it's you, but also can't rule you out, so people cut a deal.