An antiques dealer has pleaded guilty to the murder of his seven-year-old daughter.
Robert Peters throttled Sophia with a dressing gown cord in the family home in Wimbledon, south-west London, on 3 November last year.
He then called police to report what he had done and the child was rushed to hospital but she died the next day.
The 56-year-old had denied murder but changed his plea on the third day of his trial at the Old Bailey.
He had admitted manslaughter by reason of diminished responsibility, saying he was depressed and hearing voices at the time.
The jury heard Peters had claimed he wanted to spare his daughter "pain" after he feared financial ruin.
Sophia was strangled just over a month after her depressed and suicidal father was found not to be a risk by a child protection team.
In a police interview played in court he told officers he had become "too tormented with my life" and "wanted to do away" with his entire family, but could not.
Peters, who owned an oriental antiques business based in Kensington, told officers he was struggling and expected to go bankrupt within months, meaning the family would lose everything, including their home.
Speaking about Sophia, he said he did not consider himself to be a "good father" and blamed his "personality" for not loving his daughter as he should.
He also said he had recently returned to the family home after the end of a two-and-a-half year affair with a married Home Office official.
Prosecutors said that while Peters suffered from a depressive illness of "moderate severity", the condition "was not enough to enable a killing to be reduced from murder to manslaughter".
In the months before the killing, Peters searched the internet for "serial killers", "treatment of child killers in prison" and "premeditated murder", the jury heard.
Inquiries later showed Peters' business was not in trouble and he had money in the bank.
The court heard Peters waited until his wife Krittiya had gone out before he woke Sophia up in bed by tying a cord around her neck and throttling her for up to half an hour.
When she asked him what he was doing, he replied "sorry" but carried on as she struggled.
Police arrived at the home in Blenheim Road after Peters called 999 and calmly told them: "She's upstairs. I've strangled her."
Peters' ex-wife also told the court the antiques dealer had throttled, head-butted and attacked her during their marriage between 1994 and 2009.
Francine Peters said he "grabbed me around the neck" so hard that it left her with "marks", 20 years before he strangled Sophia.
The judge, Mr Justice Edis, adjourned sentencing until Monday to set a minimum life term.