Two girls accused of murder took a selfie showing them stood in front of their alleged frail victim just hours before she was killed, a court was told.
The jury was told Ms Wrightson had dark marks on her face in the selfie taken by one of the girls that were not present earlier in the night.
But the court heard it was not possible to say whether the marks were injuries.
Forsensic expert Stephen Cole told the court he had compared the selfie taken around 9pm with CCTV footage from a local store about 90 minutes earlier.
He said he identified six areas of marks to the face which were not present on the earlier picture.
Asked by Nicholas Campbell QC, prosecuting: “Can you see any marks on her face which had not been present at 7.30pm?” He replied: “Yes”.
He was then asked: “Did you see any evidece of those marks in the post mortem photos?” To which he replied: “I did, yes.”
But he was asked by Jamie Hill QC, defence for the older girl: “You can’t say that the areas you have identified as having dark skin tone, you can’t say that those area injuries?” To which he relied: ”No”
One of the teenagers accused of murdering tragic Angela Wrightson in her home told police she got blood on her clothes because she helped the 39-year-old.
Two girls, now aged 14 and 15, deny murdering Ms Wrightson in her home in Stephen Street, Hartlepool, in December 2014.
The jury was read a prepared statement which the older girl had made before her first interview.
It said: “I am not responsible for the murder of Angela Wrightson.”
It added that the pair had found Ms Wrightson with blood on her head when they called at her house.
The statement added: “When I helped her sit up, I did get some blood on my hands, I may have alswo got some blood on my tracksuit bottoms.”
The case at Leeds Crown Court continues.