Woolwich murder suspect Michael Adebolajo was pushed against a window by prison officers, knocking out two of his teeth, his brother has claimed.
Jeremiah Adebolajo told the BBC that he speaks to his brother almost daily and had also spoken to his lawyer and to the governor of Belmarsh Prison, where his brother is held.
Five prison officers were suspended over the incident, which occurred on Wednesday at the prison in south east London. All members "strenuously deny" any wrongdoing.
More top news
West Yorkshire Police confirmed a 32-year-old woman was taken into custody in connection with the alleged threats.
Five women shared their views about whether Hillary Clinton's Democratic presidential nomination is a defining moment in US history.
The patient fired several shots at the doctor in a Berlin clinic before turning the gun on himself.