Nicole Smallman and Bibaa Henry had been celebrating a birthday with friends in a London park the night they were stabbed to death. The sisters had stayed behind after everyone else had left just after midnight. Now, five days after their bodies were found, detectives have said they believe they were murdered by a stranger. As the hunt for the killer intensified, the Metropolitan police said whoever murdered Smallman, 27, and Henry, 46, may have been injured during the attack, which may have caused significant bleeding. An extensive search is ongoing at the crime scene in Fryent Country Park in north-west London, and officers are trawling through hundreds of thousands of tonnes of rubbish from a local refuse depot in search of items they believe were mistakenly cleared from the scene. A 36-year-old man arrested in south London on suspicion of murder this week was subsequently released with no further action in connection with the killings. The bodies of the sisters were discovered on Sunday in the park, a well-known spot for looking out over the capital, where two days earlier they had met friends and family to celebrate Henry’s birthday. People gradually left throughout the evening and by about 12.30am on Saturday only Smallman and Henry remained. Officers believe they were murdered within the next couple of hours. Both women were reported as missing to police late on Saturday when they had not returned home. DCI Simon Harding said: “This is an unthinkably harrowing and tragic incident and my first thoughts remain with Nicole and Bibaa’s close family and friends who are going through the most unimaginable pain and suffering. “There have been a number of factors involved in both the incident and the aftermath which have required extra time and care in enabling us to create a clear picture of what has taken place. But what we can now say with some certainty is that Nicole and Bibaa were murdered by someone who was unknown to them.” Killing by a stranger is rare. The most recent figures on homicide from the Office for National Statistics showed that six out of 208 adult women killed in the year to March 2019 were killed by a stranger – less than 3%. The two women were the daughters of the Church of England’s first female archdeacon from a black or minority ethnic background, Wilhelmina Smallman, known as Mina. She was the archdeacon of Southend in the diocese of Chelmsford until her retirement in 2016. Henry, who lived in Brent, was a senior social worker at Buckinghamshire council and a mother of one. Buckinghamshire council’s cabinet member for children’s services, Mark Shaw, said: “We are all deeply shocked and distressed … Bibaa was a well-respected, well-liked and highly valued member of our social care team. “Bibaa was committed to caring for and supporting children and young people across Buckinghamshire. She will be very much missed by all of us here at the council.” Smallman, who lived in Harrow, was a freelance photographer and graduate of the University of Westminster. Paisley Billings, an actor from south London who appeared in the Channel 4 reality TV programme Tattoo Fixers, described Smallman as a “joy to be around”. “Your energy was beautiful, kind and infectious,” she wrote on Twitter. Close relatives of Smallman said they were too upset and shocked to comment at this time. Bouquets of flowers have been laid at the entrance to the park, including one from Henry’s daughter that read: “Mum I miss you so.” The acting bishop of Chelmsford, the Rev Peter Hill, said: “We are devastated to hear of the tragic deaths of Nicole Smallman and Bibaa Henry in north London at the weekend … This is heartbreaking news and the thoughts and prayers of everyone at Chelmsford diocese are with Mina and her family. We ask that their privacy is respected and for everyone’s prayers at this most difficult of times.” Smallman had recently started working for a marketing firm called BALL Events and Promotion based in Watford. A statement from the company said: “In the short time that Nicole worked with us she made a massive impact on everyone that was lucky enough to be around her. She quickly became a major part of our team … and had become a real friend to those who worked closely with her. “Nicole was … a genuinely kind and caring person with always ready to help anyone. We are all in complete shock over what happened. Nicole will be truly missed by us all.” The community near Fryent Country Park have been left shocked by the disturbing events. Shama Tatler, a councillor for Fryent ward, said: “Everywhere has its issues but the park has always been a place for families. It’s unusual it happened in the area, it’s recognised as a family area and we’re just shocked that anything would happen let alone something like this.” Harding appealed for members of the public to come forward if they know someone who had been wounded in the last week and had not been able to account for their injuries. He said officers believed the suspect left the park via the Valley Drive entrance “At this stage we don’t know why this awful attack took place and any information we can gather will help us further put the pieces of the jigsaw together,” he said.