The body of a teenage babysitter who was stabbed to death in her sister's home as she looked after her young niece and nephew was found by her mother, police have said.
Chatherine Wynter, 19, also known as Katie, was staying at the house on Boxing Day night while the children's mother was away.
Miss Wynter's mother found her body when she called at the address in Borehamwood, Hertfordshire, at 8am the next day, Detective Superintendent Michael Hanlon said.
He said the children, aged three and four, were still in the house but had not been injured.
Specially-trained officers are interviewing them and do not yet know how much they saw or heard of what happened to their aunt, who regularly babysat as a favour to her sister.
The interviewing process is expected to take some time because of their young age. "Obviously the most important issue is the children's welfare," Mr Hanlon said.
He said an 18-year-old man from Borehamwood, who was arrested on Tuesday evening, remains in custody, and a 26-year-old man from Islington, north London, who was arrested on Tuesday afternoon, was released with no further action.
A post-mortem examination confirmed that Miss Wynter, who also went by the surname Briscoe and lived elsewhere in Borehamwood, died as a result of stab injuries.