There is a LOT of circumstantial evidence against Bellfield & no forensic evidence against Stone. This is from an article 6 years ago, when his legal team were trying to get an investigation opened into Bellfield following the Milly Dowler conviction :
Bellfield's ex-girlfriend Emma Mills has claimed that he used to drive to Kent in the 1990s to sell drugs and work as a wheel clamper
Josie described a 'beige' Ford at the murder scene. At the time, Bellfield was driving a beige E-registered Ford Sapphire which he later reported stolen
Bellfield, who was obsessed with schoolgirls, abducted Milly as she walked home from school. Lin Russell was walking Megan and Josie home at a similar time after a day at school
The Russells were attacked from behind by a man with a hammer, the same method Bellfield used to kill Marsha McDonnell in 2003 and Amelie Delagrange in 2004
Bellfield is 6ft 1in. Josie described her attacker as being a little taller than her father, who is 6ft. Stone is 5ft 7in. The e-fit issued by police bears some likeness to Bellfield, with a round face and chubby cheeks. Stone is thin-faced
Josie said her attacker had spiky hair – worn in a similar style to Bellfield
A confession allegedly made by Stone to a drug addict in an adjoining cell through a gap in some piping is still claimed by his lawyers to be unreliable
A shoelace used to tie up the Russells contained DNA traces from other people and not Stone. His legal team want to conduct new forensic tests on it but say that they were sent an 'empty envelope' by Kent Police
re the "stolen" car - didn't he do the same thing with a red car in the Milly Dowler case?
Stone was convicted partly because he once hit somebody with a 'hammer' - but he hit a man, who was already attacking him, & it was a mallet which happened to be there. Hitting women & children from behind with a hammer is what Bellfield does 
& Stone has always denied it.