The mother of a four-year-old girl left home alone was questioned by police under caution today after she returned to Britain.
Police found the girl after her 16-year-old brother was arrested along with another boy of 16 on suspicion of driving offences.
The mother is understood to have gone abroad on holiday to an undisclosed location, leaving the little girl's brother in charge of her care in Crawley, West Sussex. It is not known how long the girl had been left on her own.
The discovery of the girl was made after the two teenagers were stopped by police in the Maidenbower area at around 1am on Tuesday.
The driver was arrested on suspicion of taking a car without the owner's consent, Sussex Police said.
The second boy was held on suspicion of being carried in a stolen vehicle and child neglect. Both have been freed on police bail until September 27.
Today a police spokesman said the girl's mother had returned last night and has been spoken to under caution.
Sources said she was not arrested because it is not an offence to leave a young child in the care of a 16-year-old unless it places them at risk.
The spokesman said: "The mother of the four-year-old girl voluntarily attended Crawley police station today where she was spoken to, under caution, by officers from Sussex Police child protection team.
"At this stage the investigation is ongoing in conjunction with Social Services."
A source said earlier that the mother was expected to receive advice.
A county council spokesman said that they had no comment to make because inquiries were continuing.
Chris Cloke, head of child protection awareness at the NSPCC, said more than 9,000 calls were received by them last year about child neglect, many relating to children left home alone.
He said: "Children under 16 shouldn't be left alone overnight and we would say that children shouldn't be left in the care of someone who is under 16.
"In all situations, parents need to discuss with their children how they feel about being left home alone, and parents who do so should minimise any risk to them regardless of how long they are away.
"If the child does feel happy being left alone, then we would ask parents to make arrangements for someone to keep a watchful eye on them.
"Is there a relative they could stay with or a neighbour to check on them? At the absolute basis of this is, is the child happy?"