Murdering at the school

The headmaster

Kyle entered the office and saw his dad. Jimmy was with him. Percy and the headmaster were also there.
"DAD"-said Kyle running to his dad.
"We've got to talk Kyle"- said the headmaster Pincher.
After explaining everything to the boys Frank had to ask the hardest question of his life.
"Kyle, I'm sorry to ask you this, and Jimmy the question is also valid for you, do you know anything about this crime?"
"What do you mean dad?"
"Your dad is asking you where were you when Henry died"- said Percy
"I was buying a pen in the school shop"- answered Kyle.
"So the shop assistant can be your alibi Kyle, can't she?"- said the headmaster
"No, she can't"- said Kyle
The whole room looked at him.
"We have got our killer"- said Percy
"SHUT THE FUCK UP PERCY"- said Frank
"Don't forget I am your boss, Frankie"- said Percy
"HOW COULD YOU EVEN THINK I KILLED HIM"- shouted Kyle- "The truth is that I didn't really bought a pen, I just wanted to spend some time alone, that's it".
"Do you really think he would kill his best friend, Percy?"- said Frank
"Frank is right, Percy, but there's just a little problem, isn't it?"- said the headmaster making a little smile- "No one besides the people who are present in this room and the ones who saw the dead body will now about this. If you little kids or you and you're friend, Frank, tell this to anyone, you and Charles will lost you're jobs."
"You don't have the authority to make me lose my job"- said Frank
"You are right, I don't but Percy does" said the headmaster.
"But we will have to close the school, and we will have to put more officers on the case to find these killer! How are we supposed do to that without this come to public?"- said Frank
"It's simple. You won't"- said the headmaster
"Can't we just close the school.....? said Frank
"If the school closes people will know that something happened. If they now that some student was killed here, the school will lose all their students"
"You are telling me that you will let this killer go ? What will you say to everyone who was on that buildings and saw the cops entering the school"- said Frank
"I will say that it was a false alarm and to the ones who saw the dead body I will pay"- said the headmaster- And now you three  get out, and if the kids talk, mr Frank gets fired"
"What do we do dad?"- asked Kyle
"We will have to do what he says"
"But dad..."
"Trust me Kyle"-said Frank - "Oh, and one more thing Mr Pincher. How did Henry die?"
" He had an heart attack"- answered the director
"Oh, if that's it, my son is sick too, he can't go to school"- said Frank
"As you wish"- said the headmaster
"What about my sister?"- asked Jimmy
"Don't worry, she will be ok"- said Frank