The murder puzzle

"We went through a simple security check," the police officer said, holding the Courier Mail."At least there were no explosives or electronic components, but we can't be sure if there was poison or virus powder."

"Leader, why don't I inform the explosion team or the bio-experimental Department? Hello ... Leader, leader ..."

Before the police officer could finish his sentence, Zhao Yu tore open the email directly!

"Woohoo ..." The crowd was shocked and took a few steps back.

"It's just an email. Look at how scared you are!" Zhao Yu grumbled,"don't forget that the skull is in our hands. At a time like this, there's no need for Liang Weiyi to play dirty tricks on us!"

As he spoke, he tore open the mail and took out a piece of paper. On the paper, there was a crooked Chinese character written with a colored pen: