Merseyside Police Officers make affirmative statements about number of comments and threats made via social media.
"Merseyside Police would like to remind social media users than any offences including malicious communications and threatening behaviour will be investigated."
Karius later allowed a Gareth Bale shot to squirm in for Real's third as the Spanish club won their third consecutive Champions League trophy.
On Sunday, he posted on social media: "I'm infinitely sorry to my team-mates, for you fans, and for all the staff."