IEA Section 10

Where there is reasonable ground to believe that two or more persons have conspired together to commit an offence or an actionable wrong, anything said, done or written by any one of such persons in reference to their common intention, after the time when such intention was first entertained by any one of them, is a relevant fact as against each of the persons believed to so conspiring, as well for the purpose of proving the existence of the conspiracy as for the purpose of showing that any such person was a party to it.