Becky's step-brother, Nathan Matthews, and his girlfriend, Shauna Phillips, are reportedly being held by police on suspicion of murdering the teenager. Officers must either charge or release them by this afternoon.
Police confirm the female suspect, who is reported as being Shauna Phillips, was taken to hospital last night after feeling unwell.
She has since returned to custody.
Becky Watts' uncle speaks exclusively to ITV News following the arrest of two people on suspicion of her alleged kidnap and murder.
Sam Galsworthy, uncle of missing Becky Watts, has spoken about the family's anguish as the search for her continues and they wait for news.