Why were the Enron executives arrested?

Question

They weren’t entitled to the compensation they earned? What was the evidence against Ken Lay and the rest?

I don’t understand 

Answer 1

let say your bank balance reads $1400.

now lets say you force your internal company accounts team to add an extra 3 zeroes to that end of that balance

your balance now reads $1400000 lol

thats what Enron were doing back in those days.

Answer 2

Because insider trading and faking your books for a publicly held company is illegal.