Robert McWhir was seen “holding Marissa Aldrich under water” on the night she died, Cambridge Crown Court heard today (Monday).
Peter Gair, QC, continued delivering his opening of the prosecution's case and told the jury that a witness rang McWhir at 2.14am and, after hearing the defendant say "I'm killing her, I'm killing her", he ran to Love's Farm.
McWhir, Marissa and a witness had all been at a house party in Cambridge Road, St Neots.
Mr Gair said when the witness reached the scene he wrestled with McWhir and managed to lift Marissa out of the water, but she felt heavy and he believed she was already dead.
McWhir, 26, of Potton Road, St Neots, is charged with the murder of Marissa Aldrich, 29, on December 22, last year, which he denies.
Mr Gair said the witness panicked and ran from the scene, but several more people began searching the area after being alerted by the witness.
"Several people were searching for Marissa using their mobile phones as torches," said Mr Gair.
"Marissa was found face-up in the water and she was unconscious."
He told the jury that police officers, paramedics and Magpas attended the incident, but Marissa had gone into cardiac arrest and was not breathing. Attempts were made to revive her at the scene and she was taken to Hinchingbrooke Hospital where she was pronounced dead at 3.54am.
Mr Gair said post-mortem evidence to be heard later in the case will show Marissa had injuries, including bruises and scratches, to her arms, face and torso. Vegetation and silt was also found in her stomach, hair and airways.
Mr Gair described the findings as "classic features associated with drowning".
He said there were also signs that Marissa had been held face-down and some of the injuries were possibly from a struggle from Marissa being held down in the water which caused her to drown.
Toxicology tests showed she had some cocaine and cannabis in her system, but her alcohol level was below the legal limit to drive.
McWhir was arrested the following day and denied knowing Marissa, and said he wasn't at Love's Farm.
Mr Gair said he was also asked by officers at a later date: 'was she [Marissa] scared of you?' and he told them 'more than likely'.
The jury were told McWhir had previously pleaded guilty to attempting to pervert the course of justice after he was heard attempting to blame someone else for Marissa's death during a telephone call he made from prison. He also pleaded guilty to breaching a restraining order.
The trial continues.