Mark Valera (previously Mark van Krevel) (born 24 April 1979) is an Australian serial killer who was convicted in 2000 of the murders of David O'Hearn and Frank Arkell in Wollongong, New South Wales. Valera handed himself into police after the murders, and in court accused his father of violent and sexual abuse, citing this as the reason he himself turned violent. His sister, Belinda van Krevel, later organised for their father to be murdered by a family friend. Valera is currently incarcerated at the Goulburn Correctional Centre, where he is serving an indefinite life sentence with no possibility for parole.