Waterford woman Meg Walsh died from at least two blows to the head from a heavy object, the Central Criminal Court has been told.
John O'Brien, Ms Walsh's husband, denies murdering his 35-year-old wife in October 2006.
Ms Walsh's body was found in the River Suir on 15 October 2006, she had been missing for two weeks.
The court heard Ms Walsh was naked when she was found and had suffered three fractures to her skull as well as injuries to her shoulders, right arm and left hand.
State Pathologist Dr Marie Cassidy said the fractures to her skull were consistent with two blows from a heavy blunt object.
She said a crook-lock, recovered by gardaí, could have caused the injuries.
Dr Cassidy said it was not possible to establish exactly how long Ms Walsh had been in the water but she had been there at least several days, but she could not be more specific than that.
She said it was also not scientifically possible to establish whether or not she had been dead when she entered the water or whether she died afterwards.
However, she concluded the injuries to Ms Walsh's head alone were sufficient to cause her death.
CCTV evidence
Earlier the court heard that in an interview with Mr O'Brien, gardaí put it to him that he had not spent the day Meg Walsh disappeared in Tramore, reading the papers, as he had claimed.
Gardaí put it to him that he had in fact been picked up by CCTV in Waterford city centre. Gardaí also claimed Mr O'Brien was not where he said he was on the following evening either.
Mr O'Brien had claimed he had spent the evening driving around to see if he could locate his wife's car.
It also emerged today that Mr O'Brien admitted to gardaí that he had assaulted Ms Walsh less than two weeks before her disappearance.
In a statement to gardaí after her disappearance, he admitted that he 'lost it' and hit her on the head after a row on 20 September. Ms Walsh later reported the assault to gardaí.
In a statement given to gardaí on 4 October 2006, John O'Brien described how he met Meg Walsh when she was on holiday with her first husband in Crete in 2000.
He said her marriage was breaking up at the time. They started an affair and eventually married in October 2005.
He told gardaí they had their ups-and-downs and would argue about money.
On 20 September, he said Meg started shouting at him after they arrived home from a night out with his parents.
He said he was going to bed. She grabbed him, he said, and he pulled her hand away and she screamed.
He said he lost it. 'I hit her on the back of the head with my fist', he said, 'and told her to stop screaming'.
He said he put his hand over his mouth to stop her screaming and he dragged her back in from an open window, hurting her hand.
He said Meg told him a day or two later she had told the gardaí and if he ever did it again she would have him prosecuted.
Later he said he pleaded for forgiveness and he agreed to sign the house into her sole name 'if that was what it would take'.
He also told gardaí he last saw his wife at 5pm on 1 October 2006 and heard her go out at 8.30pm.
Detective Inspector John Hunt said Mr O'Brien phoned him on 5 October to ask if the gardaí were finished with his car and the house.
The Inspector said he never asked about his wife or if they had found his wife and he thought that was very unusual.
