Police investigating the murder of a soldier hacked to death on a busy London street were looking on Friday into whether the two suspected killers, British men of Nigerian descent, were part of a wider conspiracy.
The two suspects, aged 22 and 28, are under guard in hospitals after being shot and arrested by police following the murder of 25-year-old Afghan war veteran Lee Rigby on Wednesday in broad daylight. They have not yet been charged.
Detectives were also questioning another man and a woman, arrested on Thursday on suspicion of conspiracy to murder, as they tried to determine whether those responsible had links to militants in Britain or overseas.
"This is a large, complex and fast-moving investigation which continues to develop," police said in a statement.