Police are investigating how $20 million was illegally transferred from the Trust's bank account.

transferred 是动词 transfer 的过去分词形式。transfer 由前缀 trans-（表示"跨越、转移"）和词根 fer（来自拉丁语 ferre，意为"携带"）组成，意思是"转移、转账"。在句中表示资金被非法转移的动作。