Officers searched the family home in Bradford of the babysitter, Rachel Rooney, 15, removing items of property and purging the drains around the house in what detectives said was a routine operation.
The children were knifed to death on Saturday night in a scene described by police as "total carnage".
Jonathan's mother, Denise Copley, and his two elder sisters found the bodies in an upstairs bedroom when they returned home from a party shortly after midnight.
Yesterday, a motorcyclist wanted for questioning was eliminated from the inquiry after answering a police appeal for him to come forward. He had called at the Copley home in Little Horton, Bradford, on Saturday evening but left after being told that the person he wanted to see was out. He was able to help police narrow down the time of the murder to between 9.30pm and 12.30am.
A second man, described by Detective Superintendent Malcolm Mawson as a family friend, was also released yesterday after providing blood samples and other "legal niceties". Det Supt Mawson said the man was not regarded as a strong suspect but he did not say why he had been detained. Prayers were said at Jonathan's school, South Mere First, and Rachel's, Grange Upper School, where tearful pupils observed a two-minute silence.
Richard Thompson, head of Grange Upper, said that pupils were heartbroken, unwilling to accept that Rachel had been murdered.
"Rachel was one of those people who would make you feel better by just speaking to her," he said. "She was incredibly positive, responsible and reliable and was making good progress at school." Outside Jonathan's school yesterday, one parent with a six-year-old son, asked: "How do you explain to kids so young what has happened? It's bad enough for adults to even try to understand."Reuse content