They are due to appear in New Plymouth District Court tomorrow.
The spokesperson said police are still in the early stages of their inquiries, however, and are still working to establish the full circumstances of Marshall's death.
Police are also appealing to the public for sightings and any information regarding two specific vehicles.
The first is a grey or silver 2005 Mazda Axela hatchback, with a damaged front driver's side headlight, any time from August 2, particularly in the New Plymouth area, including Blagdon on August 3 at about 5.30pm.
The second vehicle is described as a smaller Japanese hatchback, possibly blue in colour, and about a 2010 year model, seen in the vicinity of 100 South Rd on August 3 at about 6pm.