That day you saw Katelyn at the beach also just so happened to be the day she got arrested...
For murder
It wasn't proved that it was Quinn until they found one of her quality designed bullets, red and blue marked with KQ.
It should have been obvious it was her but when Brendan was set up to investigate.. It lead to her.

Now whenever Brendan gets the opportunity to say it allowed, he will.. during free time in history class is when I started to happen:

"Hey Insanity!" Brendan had turned around yelling at Katelyn in the back if the class room, "I heard you met someone in jail?" Katelyn's face lights up, "Not so brendan, I wasn't able to get the time of day from ANYONE!" she yells.

What do you say?:
A) "Break it up! Save the fights for the comics!"
B) "Where is the popcorn?"
C) "GO BRENDAN!"
D) "Katy chill out some!"
E) your own answer