Weird Rule: Don't Look in the Mirror at Midnight

My name is Lu Ye, and I am a criminal police officer. There have been four bizarre deaths this month, all of which were men living alone, all caused by cardiac arrest. It wasn't until tears of blood flowed from the corners of the fourth corpse's eyes that I discovered one thing—— When they died, they all looked in the mirror. What's even weirder is that a line of words suddenly appeared in my mind: [Rule 1: Do not look in the mirror after 12 midnight. I don't know where this line comes from. But I know that if this is true, the next person to die... It could be me.