There is evidence that they colluded to deceive the investors.

colluded 是动词 collude 的过去式。collude 由前缀 col-（表示"共同"）和词根 -lude（来自拉丁语 ludere，意为"玩、耍"）组成，字面意思是"一起玩把戏"，引申为"勾结、共谋"的意思。