Two people were killed in Kasungu District on Sunday for being suspected to be blood suckers, bringing the number of those killed in such circumstances to five since last week.
The three others were killed four days ago in Mzimba and Chitipa districts.
On Sunday, police said they had arrested 12 people in relation to the murders.
Kasungu Police spokesperson, Harry Namwaza, said no one has been arrested in connection with the death of the two people whose identities are not yet known.
In a statement on Sunday, signed by National Police Public Relations Officer, James Kadadzera, the security agency warned that anyone involved in the malpractice will be arrested.
In 2017, the blood suckers issue resurfaced in the Southern Region and nobody was medically proven to have fallen victim.
In that year, nine people were killed on suspicion that they were blood suckers, prompting President Peter Mutharika to visit some of the hotspots and advise people against killing each other based on hearsay.
In a statement that year, Society of Medical Doctors also condemned the lynching of the suspected blood suckers, saying there was no evidence that anyone had their blood sucked and attributed the claims to Shared Delusional Disorder.