There was a mass breakout from Azkaban three hours and thirty seven minutes before the Battle of Hogwarts.
Block 17 of the Mugglborn wing gets loose. Someone didn't check all of the new arrivals coming in. Apparently someone had an extra wand up their sleeve. Before the gates can shut, twenty three muggleborns are out of the prison and on the run.
Justin Finch-Fletchley is among them. When he first stumbles out of the prison with his twenty three fellows after defeating the shocked ministry workers that had tried to lock them in again, he can hardly believe how beautiful the cold sea air feels against his face. He has no sense of time. He doesn't know how long it's been since he went before the Ministry Council in September and was sentenced for life for being a wizard.
All he knows is that he's cold and he has a wand. So he decides to go home.
It's a stupid plan. Hogwarts is, after all, the place that turned him in for being a muggleborn. He knows that Snape (the traitor) runs it now. He knows this.
But he is tired. So tired. And he's cold. And he has a wand. So he apperates.
When they find him, it takes three days to identify him. No one recognizes the skeleton boy in the grey rags with no shoes who was found surrounded by the two Death Eaters he killed. It's Susan Bones who finally recognizes him by a birth mark on his left wrist. She becomes so hysterical when she realizes it's him that it takes two sleeping draughts and four days in St. Mungos for her to recover.
Justin's parents, his father that was so excited to have a magical son, his mother who wanted so badly for her son to go to Eaton, are told that their son died a hero's death. They are not told that he spent the last eight months of his short life in a prison that made nightmares seem pleasant. They are not told that he was completely unrecognizable when he was found. They are not allowed to see his body. The wizarding world cannot bear to tell Mr. and Mrs. Finch-Fletchley that their world failed their son so completely.
The magical world is not yet ready for that truth.