Four people are being questioned by police in connection with the death of teenager Anthony Walker.
Anthony Walker was attacked in McGoldrick Park, Huyton
A-level student Anthony was found on 29 July with an axe embedded in his head in McGoldrick Park, Huyton, Merseyside.
Merseyside Police said on Tuesday four people were being held on suspicion of perverting the course of justice.
A 31-year-old man and a woman, aged 34, from Kirkdale, Liverpool, and two men, aged 18 and 25, from Huyton, are being questioned at local police stations.
Two men, Paul Taylor, 20, of Elizabeth Road, Huyton, and Michael Barton, 17, have already been charged with Anthony's murder and are due to go on trial.