A Polish sex attacker who was allegedly murdered by a passer-by who intervened as he "molested" a teenage girl was found to have sustained five stab wounds, a jury was told.
Janusz Smoderek, 48, could have "walked and talked" for minutes before collapsing at the spot where he was found dead, a Home Office pathologist said.
Stephen Sleaford, 38, denies knifing Smoderek, 48, after going to help the crying 18-year-old as she was sexually assaulted by the Polish flower packer.
A murder trial jury was told Sleaford and two friends were walking home from their local pub in Boston, when they heard the girl's "hysterical screams" after Smoderek grabbed both of her breasts.
Smoderek, whose wife had remained in their native Poland, had earlier been spotted "hovering" around the town centre on CCTV after visiting a local lap dancing club.
The prosecution accept Sleaford at first acted in a "lawful and praise-worthy" manner when he and another man separated Smoderek from the frightened teenager who was targeted as she walked home alone at 4am.
But having intervened to help the girl and to make sure Smoderek was no longer a threat, it is alleged Sleaford then knifed the sex attacker in the chest as they wrestled on the floor.
A pathologist who examined Smoderek's body after he was found in a nearby garden the following morning said the factory worker had sustained five stab wounds to his chest area.
Professor Guy Rutty told Lincoln Crown Court one of the wounds was 16cm long and had penetrated the lower part of Smoderek's right lung.
But Professor Rutty concluded the injury which caused Smoderek's death was another wound to the left side of his chest which penetrated his heart sack and left a hole in his heart which led to fatal internal bleeding.
When asked how long it would have taken for Smoderek to die, Professor Rutty said: "It could have been minutes. He could have walked, talked and moved."
Dr Rutty told the jury "moderate force" would have been needed to inflict the stab wounds.
The jury heard a bruise consistent with Smoderek receiving one punch was found on his face but there was no evidence of any defensive injuries from a knife. Other injuries to Smoderek's body could be explained by him falling through a hedge.
Toxicology tests showed the father-of-three was nearly three times over the drink-drive limit for alcohol.
Sleaford denies the murder of Smoderek on September 11, 2011.
The trial, which is expected to last four weeks, continues.