A British man wanted over the deaths of his American wife and baby daughter has agreed to be extradited to the US.
US prosecutors believe Neil Entwistle intended to kill himself
Neil Entwistle's lawyer said he was anxious that more delays would have added to his wife's family's distress.
The 27-year-old, arrested on Thursday, appeared before Bow Street magistrates. He faces charges of murder and illegal possession of a firearm in the US.
The bodies of Rachel Entwistle, 27, and Lillian, nine months, were found in Hopkinton, Massachusetts, last month.
Appearing outside the court, his solicitor, Judith Seddon, said her client could return to the US "within days".
She also denied he had changed his mind after indicating on Thursday that he would not consent to extradition "at this stage".
He had "reserved" his position so as to "think overnight", but had always inclined towards consenting, she said.
"He has consented at the earliest opportunity because he wants to co-operate with the authorities in any way that he can and he is anxious that a delay may cause his late wife's family, and his own, additional distress, something he wishes to avoid," she said.
"He believes that he will receive a fair and proper hearing in the USA on these very serious allegations."
In a press conference in the US after Mr Entwistle's arrest, Middlesex District Attorney Martha Coakley revealed she believed he had intended to kill himself after shooting his wife and child.
She said evidence suggested Mr Entwistle had shot the pair as they lay in bed on the morning of 20 January, with a gun he had obtained from his father-in-law Joseph Materazzo.
Mr Entwistle left the US after the deaths and had been staying at his parents' home in Worksop, Nottinghamshire.
The family of Mrs Entwistle said in a statement they were "deeply saddened" by his arrest.
Ms Coakley said forensic evidence linked the gun to Mr Entwistle and his wife.
The Entwistles had moved to the US after their daughter was born
She said, after the shootings, Mr Entwistle had returned the gun to his father-in-law's home, before making preparations to leave the country.
He then bought a one-way ticket to the UK and left at 0815 local time from Logan airport, in Boston, on 22 January, the prosecutor said.
"Authorities went to the UK to pursue that investigation. We explored motive, with witnesses, with information from searches, internet capabilities."
She said this information, combined with forensic evidence, gave "probable cause" to seek Mr Entwistle's arrest.
Ms Coakley said Mr Entwistle had had debts in England when he moved with his family to the US and that his new internet businesses were failing.
She added that he also had new financial obligations, including the lease on his five-bedroom home.
The bodies of Mrs Entwistle and Lillian were discovered under a pile of blankets in a bedroom in their house on 22 January.
Mr Entwistle was arrested by Metropolitan Police officers at Royal Oak Tube station, west London, on Thursday.
If US courts convict him of the murders, he will face life imprisonment with no possibility of parole.
Massachusetts does not have the death penalty.