I worry the way that this has all happened on social media may save him. Police generally do not release people on bail without charging them when there is strong evidence.
This suggests there is not sufficient evidence to charge him. Investigations will continue, I guess, but there could be a future where this does not result in a prosecution.
He`s been released, because, as it stands, the evidence hasn`t met the " threshold " at which the CPS would charge - IE : " is there a realistic chance of a successful prosecution with the evidence as it stands ".
The social media photos and voice recording will be evidence, but if he has said " no comment" ( which is what I`d advise him to do, if I was his brief ", you have to provide evidence, that he he caused the injuries, that it was his voice on the recordings and that a sexual assault took place.
To prove her injuries, you`d need one or more from the following - a witness, similar fact ( he`s done it before ) CCTV, injuries to his own hands etc.
The recording would have to be sent off to a voice expert ( takes time )
She`d be medically examined and if that didn`t show any sign of " forced penetartion ) you`re struggling.
Then there`s evidence from, the first person she told, forensic evidence from the likes of her clothes, underwear, bedding etc.
He`ll have to provide forensic evidence, in the form of swabs, clippings, etc. for comparison.
All the forensic stuff then has to be examined ( can take a while, unless it`s fast tracked, which normally only happens there`s a child / vulnerable person involved or something like a serial rapist )
So, as you can see, without an admission, there`s still quite a bit of work to do, before it even gets to the stage where he could be charged. ( which is quite normal )
I`m not condoning him by the way.