Merseyside Police is investigating after a threatening banner was hung up near the home of prospective new Everton manager Rafael Benitez.
Benitez is the strong favourite to take over at Goodison Park following Carlo Ancelotti's move to Real Madrid earlier this month.
The proposed appointment has not gone down well with some Everton fans given Benitez's links to city rivals Liverpool, whom he guided to Champions League. FA Cup and European Super Cup success.
Sections of the Toffees' fanbase have left messages outside the club's stadium over the past week, but those protests have now turned more sinister.
Images and videos emerged on social media on Monday of a banner reading "We know where you live, don't sign" close to Benitez's family home in Wirral.
Merseyside Police has confirmed that it is looking into the matter.
"We can confirm police are investigating reports of a threatening banner at a location in Caldy today, Monday 28 June," a statement on the force's official website read.
"At around 7am, it was reported that a banner made from bed sheets had been placed over a wall and bushes on a residential driveway, with wording which is thought to target football manager Rafa Benitez."
CCTV and witness enquiries are being carried out in the area to try and trace whoever was responsible.
Detective Inspector Darren Taylor added: "This message has understandably caused some distress and worry for residents in the area.
"Due to the football language used, we suspect that it was aimed at Rafa Benitez – but whoever placed the message left it outside the wrong house.
"If anyone has information about who produced the banner or helped to put it up, please let us know as soon as possible."
Benitez spent six years with Liverpool in total before departing in 2010.
The Spaniard apologised in 2007 for labelling Everton a "small club" following a goalless Merseyside derby.