Vikki Thompson may have been murdered 15 years ago because she caught a man performing an indecent act, a jury was told today.

Mark Weston — from Ascott-under-Wychwood, the same village where Mrs Thompson and her family lived — today faced a jury for the second time accused of killing the 30-year-old in August 1995.

He was acquitted of murder by a jury in Oxford in 1996 but was re-arrested and charged after new forensic evidence — in the form of very small blood stains on the defendant’s boots was uncovered — the new jury at Reading Crown Court was told.

Opening the prosecution case, John Price, prosecuting, said: “Vikki Thompson was violently attacked when out walking her dog.

“She was attacked by someone who struck her repeatedly about the head with a heavy object or objects, causing skull fractures and severe brain injury from which she died six days later.

“The only witnesses who saw what happened were Mrs Thompson and her killer, who the Crown alleges was the defendant Mark Weston.”

Outling a potential motive for her death, he added: “It happens, probably, because as she walked with her dog towards the very end of the lane furthest from the village, she caught him watching her and (performing a sex act).

“(She reacted) to this in a way which prompted him to chase and fatally to attack her as she tried to flee back up the lane screaming.”

He said the attack came just 24 hours after Mrs Thompson and husband Jonathan celebrated their wedding anniversary.

Jurors heard Mrs Thompson left her home in Chestnut Drive at 4pm on August 12, 1995, and was found between 7.15pm and 7.30pm at the foot of a railway embankment off Shipton Lane.

Her husband arrived at the scene and reported she had been able to speak though “not in any coherent fashion”, Mr Price told jurors.

Mr Price said: “She was not able to say what had happened to her nor who was responsible.”

Mrs Thompson was taken by air ambulance to the John Radcliffe Hospital, Oxford but had suffered “head injuries of the utmost gravity”, Mr Price said.

Weston was arrested on September 13, 1995 and charged with murder on February 1, 1996.

A trial began at Oxford Crown Court that November and Weston was acquitted on December 3.

The case was re-opened in 2005 and Weston was arrested on October 21, 2009. He was charged the following day.

Mr Price said “important articles seized in the original investigation were re-submitted for further scientific examination”.

He said: “They included a pair of black boots belonging to Mark Weston and which had been seized from his home on the occasion of his first arrest.

“Found upon each of the boots, but which had been missed when they were first examined in 1995 and 1996, were very small blood stains, the DNA profile of which was found to match that of Vikki Thompson to a degree which proves beyond question, the prosecution submit, that it is her blood.”

He added: “In respect of certain criminal offences, including murder, the law now permits that a person previously acquitted may be re-tried if since that acquittal, there has emerged fresh evidence of his guilt.”

Weston, 35, of Dawls Close, denies murder.

The trial continues.