Det Sgt Peter Ritson says there was no evidence of a cause of death.
He said the field where Becky's remains were found was a hard soil. She was buried in only 8 inches of soil.
The Oxfordshire coroner Darren Salter recorded a narrative verdict.
On the available evidence its very likely that her death was unnatural and violent. At an unknown location at the end of 2002 or early 2003. “
More top news
We've been in awe with all the pictures you've been sending us. Here's as many as we can fit!
An exclusive ITV opinion poll shows the Lib Dems are facing electoral wipeout in the South West.
A Somerset photographer has captured a series of striking images showing a cat tussling with a mouse on a roof top.