What is that word?

I forgot that word.Could you help me please?It’s meaning is this.
“A guy in a gang has done something wrong and is caught by the police but he will be cleared of blame if he gives important information about the gang and their plan.”

Note:It’s not “informer”.Some other word.

‘squealer’? - noun

‘to squeal on somebody’ - verb

grass?

Wait I will tell you clearly.
I am gonna use that as a … in case I get caught.
Now tell me that word that fits perfectly in this sentence.

‘going to’ first perfectly - instead of ‘gonna’ which is not grammatically correct.

Do you mean ‘an alibi’? (The definition isn’t quite the same as the one you give originally though)

No not alibi but some other word and it has the same definition.

I’m running out of ideas.

Use it as a plea bargain? (Use it to get a reduced sentence for a more minor offence in return for the information)

Use it as leverage?

May be leverage.I am not sure about that.But leverage has a different meaning hasn’t it? Tell me the meaning of
I am going to use that as a leverage in case I get caught.

Not a leverage - just ‘leverage’.

I am going to use that (knowledge) to maximum advantage in case I get caught.