Officers looking into the death of nine-year-old Olivia have detained four individuals in the past 24 hours.
In relation to the Liverpool slaying of nine-year-old Olivia Pratt-Korbel, a fourth man has been detained.
The suspect, 34, was stopped on the M42 near Leamington Spa on Sunday evening.
The man, who is from Liverpool, was arrested on suspicion of assisting an offender and is in police custody.
Detective Chief Superintendent Mark Kameen said: “I continue to urge anyone who has information that can help our investigation into Olivia’s tragic murder to please come forward so we can bring those responsible to justice.
“A number of people have been arrested in respect of this investigation. However, we still need the public‘s help in ensuring that we can build a strong evidential picture so justice is served for Olivia and her family.
The latest development comes after a man, also 34, was arrested on suspicion of murder and attempted murder in connection with Olivia’s killing.