a rotten apple	bad person in a group of people who are good
an inside job	a crime committed by someone against the organization that they work for
spill the beans	to give away a secret or a surprise
point the finger at	to accuse
put a foot wrong	to make mistakes
cover ones tracks	to hide/get rid of incriminating evidence
come clean	to confess to sth
do time	to serve a prison sentence
in hot water	in trouble
carry the can	to take the blame
in hot water	in trouble
brush the problem under the carpet	to hide/ to ignore sth illegal/ unpleasant/
blow the whistle on	to stop sth illegal or bad from happening by telling the authorities
catch sb red-handed	to discover sb in the act of wrongdoing
on the spur of the moment	spontaneously
get away with murder	to do sth illegal/ terrible without being punished
in broad daylight	in daylight when it is easy to see
by the book	according to the law
off guard	by suprise
cut and run	to make a quick escape
teach sb a lesson	to punish sb in order to improve their behavior