Becky Watts went missing from her family home on 19 February
Nathan Matthews, the stepbrother of missing 16-year-old Becky Watts, has been charged with her murder, Avon and Somerset Police have said.
His girlfriend, Shauna Hoare, 21, has been charged with attempting to pervert the course of justice.
The pair are due to appear before Bristol Magistrates Court at 10:00 GMT on Thursday.
Nathan Matthews and Shauna Phillips were arrested at the weekend
Four other men and a woman, all in their 20s, are being questioned on suspicion of assisting an offender.
Becky was last seen on 19 February and was reported missing the following day by her family.
On Tuesday, body parts were found at a house in Barton Hill, Bristol.