Scotland Yard has referred itself to the police complaints watchdog after a woman was found dead at a house near Hyde Park the morning after it received several reports from friends concerned about her welfare. A murder investigation was launched after police forced entry to a property in Stanhope Place, near Marble Arch, central London, at about 8.30am on Monday and found the body of Kamonnan Thiamphanit. Officers had been contacted twice by friends of Thiamphanit on Sunday evening, the day before she was found dead, because they were concerned that they had not heard from her. Their calls were graded as a medium-risk missing person inquiry at the time. Officers forced entry the next morning and discovered the body of the 27-year-old. Thiamphanit, who was known to her friends as Angela, had suffered a number of stab wounds. There had been no signs of forced entry at the property. A postmortem examination carried out on Wednesday found the cause of death to be sharp force trauma. Cmdr Owain Richards told the PA news agency: “We received two calls from Kamonnan’s friends on Sunday 7 April, raising concerns that they had not heard from her for some time. “One just after 7pm and then another one just after 9.30pm on the Sunday evening. We initially graded the missing person inquiry as a medium-risk, prior to forcing entry and discovering her body on the following Monday morning. “As her friends had contacted police and then we subsequently found, tragically, the body, we have made a mandatory referral to the Independent Office for Police Conduct, which is a standard referral in these cases to understand a review of what happened and whether there’s any lessons to be learned in relation to that.” Officers believe it is likely Thiamphanit knew her attacker and was likely last seen by her friends on Sunday. No arrests have been made. Richards added: “We believe the suspect was known to the victim in this case and our homicide detectives are working around the clock to pursue all reasonable lines of inquiry to trace the suspect, arrest them and bring them to justice. “We’re trying to piece together her background and lifestyle to help us understand the motive and the background to this matter to bring the suspect to justice.” Richards said that the family of Thiamphanit, who had Chinese, Hong Kong and Thai nationality, lived overseas and had been informed. “To lose a loved one in these circumstances is unimaginable and our thoughts are with them. We ask that their privacy is respected at this very sad and difficult time. I completely understand the shock and concern this incident has caused, especially to women living and working in the area. “I understand there is speculation about what had happened to Kamonnan. While our detectives are keeping an open mind for any motive, I can confirm that it is likely her attacker was known to her. “Kamonnan’s murder makes us all the more determined in our efforts to do everything we possibly can to keep women and girls safe,” he said. Detectives continue to appeal for information. The IOPC has confirmed the Metropolitan police referred itself to the watchdog on Tuesday. An IOPC spokesperson said: “We advised the force that its investigation should, in our view, review the police response against policy and procedure and identify whether there were any missed opportunities to find Ms Thiamphanit sooner and potentially prevent her death. “However, we noted that the timing of her death is unclear at this stage so there may be a possibility that she was already deceased prior to the police being contacted. “The force was reminded that should its investigation identify any conduct matters for any officers or staff, then a further referral should be considered.”