According to the Verdens Gang (VG) daily the traces of blood are now among the strongest pieces of evidence police now hold in the ongoing investigation into the teen's murder.
Two men - a 37-year-old from Ålesund and a 64-year-old from Vestby - are currently remanded in custody in connection with the killing.
The police are working on the theory that the 37-year-old killed Sigrid, wrapped her in plastic and dumped her on the slope where she was found on Kolbotn.
The traces of blood were later left in the caravan known to be where the 37-year-old had been living at the time of the murder.
There are several other items which link the men and their workshop to the 16-year-old's killing. These include the plastic Sigrid was wrapped in when she was found murdered and, according to a TV2 report, several straps used to bound the teen.
Furthermore, the police have been able to connect the 37-year-old's green Citroën to a toll booth on Strømsveien around the time of Sigrid's disappearance.
The 37-year-old has meanwhile denied that he was driving the vehicle at the time, arguing that there were several others who could have had access to the keys.
The police were however unwilling to confirm the information in VG's report.
"We wouldn't comment on findings that have been made in the case as it could be devastating for the investigation," said Cecilie Gulnes at Oslo police.
The 37-year-old's lawyer, John Christian Elden, declined to comment on the matter.
"I am not going to comment on this now. We hope the matter is resolved in the best possible way," he said.
Sigrid Giskegjerde Schetne disappeared on her way home from a friend's house at around midnight on Saturday August 4th, prompting a massive police and public search.