Amelia put on an invisibility cloak and made her way to Hogwarts. Amelia entered the Great Hall just as breakfast was ending and it was her great fortune that the first two people to exit the staff table and leave the Great Hall were Dumbledore and Snape himself. This provided Amelia with an opportunity to go talk to some of the other teachers and see if they would help her.
Amelia approached the staff table and removed her invisibility cloak.
"Filus, Pomona, Minerva?" asked Amelia, "I would like to ask you something. I am here to investigate Severus Snape. I would like to know what the average O.W.L. and N.E.W.T. Potions scores of the students in your houses were like in the decade before Snape came to Hogwarts and what they've been like since he arrived here."
"Well, " snapped McGonagall, "If students aren't achieving as highly as they should on their O.W.L.s and N.E.W.T.s. then that's their own fault for not putting enough effort into their work and/or not studying enough."
McGonagall stormed out of the hall.
"I don't think Minerva actually likes Snape, " said Flitwick to Amelia, "But she's so loyal to Dumbledore that she won't actually criticize or act against Dumbledore's favorite member of staff."
"McGonagall being loyal to Dumbledore is information worth filing away, " said Amelia firmly, "But would either of you be willing to answer my original question?"
"Yes," responded Flitwick, "Ravenclaws have traditionally been outstanding Potions students and in the decade prior to Snape taking over the role of Potions Master, Ravenclaws were earning average scores of O's on both their Potions O.W.L.s and their Potions N.E.W.T.s. Since Snape turned up and took that post, Ravenclaws average scores on both their Potions O.W.L.s and their Potions N.E.W.T.s. has dropped to A."
"Hufflepuffs have never been elite potion brewers, " admitted Sprout, "But in the decade before Snape they were achieving As on both their Potions O.W.L.s and their Potions N.E.W.T.s. Since Snape started teaching Potions, the average O.W.L. score in Potions for Hufflepuffs has fallen to D. Now, the average N.E.W.T. score for Hufflepuffs in Potions has actually increased to E, but that's fool's gold. Professor Snape absolutely refuses to accept students into his N.E.W.T. level courses who have not attained a grade of O on their Potions O.W.L. The improved N.E.W.T. average in Potions for Hufflepuffs during Snape's tenure is simply the result of extremely low sample size. Only a very few Hufflepuffs have ever taken Snape's N.E.W.T. level Potions course and those few have been the cream of the crop in terms of there being a few elite potion brewers in Hufflepuff. But there have been more than a few years in which NO Hufflepuff has taken N.E.W.T. Potions under Snape's regime and in most of the rest, Snape has only taken one Hufflepuff into his N.E.W.T. level classes."
"Fuck Severus Snape!" said Amelia in an icy cold voice, "Now I know why the Ministry has seen so few new Auror applicants in recent years and why St Mungo's has seen so few new Healer applicants. You have to earn a Potions N.E.W.T. to even be considered for those occupations. Snape is going to bring the whole Wizarding World into shambles with his non-teaching of such a crucial subject in our world."
"Are you planning on sitting in on one of his classes today?" asked Flitwick.
"Yes, " said Amelia in a businesslike voice, "I'm going to use my invisibility cloak."
"Sit in on his class after lunch, it's the first year Gryffindors and the first year Slytherins," suggested Sprout.
"Okay, " said Amelia, "This morning I'll go into the History of Magic classroom and interview some students there. No one pays attention to Binns anyway."
A few minutes and a few nanoseconds later, Amelia was in the History of Magic classroom, which was full of third years.
Quietly, Amelia made her way up to Angelina Johnson.
"Hey, Miss Johnson?" said Amelia, "You're not in trouble, but I want to interview you. My name is Amelia Bones and I am head of the Department of Magical Law Enforcement. I am here investigating Professor Snape-"
"It's about time someone did that!" said Angelina fiercely.
"So, what can you tell about what Snape's classes are like?' Amelia asked Angelina .
"He favors the Slytherins, " said Angelina in a no nonsense type of voice, "He bullies non Slytherin students. And I heard it through the grapevine that Snape purposely sets ridiculously easy homework and essays for the Slytherins while setting homework and essays several years above what is age appropriate for Gryffindors, Ravenclaws, and Hufflepuffs. When I was in my first year, I was genuinely stunned by how much harder Potions was not only compared to what I expected to but also how difficult it was compared to ANY other subject. Now I understand."
'More conformation of Snape's non-teaching," sighed Amelia wearily.
"And, " added Alicia Spinnet, who was sitting next to Angelina because they were besties, "Sometimes we get in trouble even when the Slytherins sabotage our potions while they always get away with anything."
"Then there's the fact, " added Fred Weasley a few seats down, "That he'll mark our potions as zeros if we make one mistake no matter how much better they are than the Slytherin's Potions."
"Plus, " continued George Weasley, "He'll give the Slytherins Os for their work as long they follow one line of the instructions correctly."
"He also taunts us about our family being poor, " added Fred, "And makes snide remarks about our supposed ineptitude in Potions."
"I've heard what I needed to here, " said Amelia firmly, "I'm going to be using an invisibility cloak to sit in on his first class after lunch. Also, if he has the Dark Mark on his arm, then I will be arresting him, and he will face a trial for being a Death Eater."
"Good, " said Angelina approvingly, "Let's get the greasy haired bastard out of Hogwarts."
"That's why I'm here, " smiled Amelia.
After lunch, Amelia used her invisibility cloak to sit in on Snape's class featuring the first year Gryffindors and first year Slytherins.
She hid away in a corner and was careful not to move or talk.
After some course introduction that sounded to Amelia that was meant to sound more impressive than it really was, Snape said suddenly. "Ah, this class contains Neville Longbottom."
Amelia listened intently for any signs of malice.
"You know, Longbottom, even when your parents were useful, which was a long time ago, they were lamentable Potion Makers. The apple won't have to fall far from the tree for you to be a dunderhead, " said Snape with a smirk.
Out of the corner of her eyes, Amelia saw tears forming in Neville's eyes and knew why; his parents had been tortured into insanity by Bellatrix Lestrange and Barty Crouch Jr. Snape was showing his true character here by taunting Neville about his parents.
Later on, Snape had the students brew Cure for Boils. Draco Malfoy made a major mistake in his potion by adding porcupine quills to the mixture while the cauldron was still on the fire.
There was a loud hissing sound and acid green smoke filled the room.
Malfoy's cauldron had melted, and his potion was seeping across the floor.
Some of the potion had splashed onto Neville and angry red boils sprung up on his arms and legs.
"Ten points from Gryffindor for appearing in such a manner, Longbottom. Go to the hospital wing and get out of my sight, " snarled Snape.
"And you, Patil?" said Snape, turning to Parvati, "Why didn't you tell him to take the cauldron off the fire before adding the quills? Thought you'd look better if he suffered? Another ten points from Gryffindor."
Parvati looked stunned. How could this be her fault.
"And before we go, " said Snape, "Twenty points to Slytherin for their outstanding Potions skills. Class dismissed."
"Stupefy!" cried Amelia, pointing her wand at Snape and stunning him.
Finally taking off her invisibility cloak, Amelia walked up to unconscious form of Snape and lifted up the sleeve of his left arm.
Not to her surprise, Amelia did indeed find the Dark Mark tattooed there, though it was deeper and more solid than any Dark Mark tattoo she'd ever seen, save for Bellatrix Lestrange's.
Amelia conjured a pair of handcuffs and restrained Snape.
When Amelia woke Snape up, she told him, "There are many issues surrounded you, but you under arrest for being a Death Eater."