ATTENDANCE records at Graham Dwyer's offices showed he was at work there on the day Elaine O'Hara disappeared, the Central Criminal Court heard.
The jury was also told there was no evidence he had left work early that day - August 22, 2012.
However, the court heard there were some inconsistencies in the records covering other dates that Mr Dwyer, an architect, had been working in 2011 and 2012.
Siobhan McEvitt, office manager at A&D Wejchert, Baggott Street Lower, was being cross-examined by Ronan Kennedy BL, for the defence.
Mr Dwyer (42), of Kerrymount Close, Foxrock, is pleading not guilty to the murder of Ms O'Hara (36) at Killakee, Rathfarnham on August 22, 2012.
Ms O'Hara, a childcare assistant from Killiney, was last seen alive near Shanganagh Cemetery in Shankill that day.
Her remains were found by a dog walker in undergrowth in the Dublin mountains on September 13, 2013.
The prosecution maintains Mr Dwyer killed her for his own sexual gratification.
Ms McEvitt told the jury that on a number of dates, it was marked in attendance records that Mr Dwyer was at work but she could not verify that he was in the building on the days.
On some dates, she told the court there was nothing in the records to say he was out of the office.
At one point there was an error in the records, when he was marked as being at a meeting in Poland on December 1 and 2, 2011. This was entered in error and he actually went on the trip the following week - December 8 and 9, 2011.
In cross-examination, Mr Kennedy put it to Ms McEvitt that she could not vouch personally for anyone being on or out of the office on a particular day.
"You are relying on the accuracy of the records and sometimes there is a conflict in the records," he said.
Ms McEvitt agreed she could not personally vouch for anyone "unless I spoke to them personally".
She then told Mr Kennedy that records show Mr Dwyer was working in the office the day Ms O'Hara disappeared.
Mr Kennedy queried attendance records and monthly timesheets for the weeks ending August 19, 2012 and August 26, 2012.
"Yes he appears to have worked a normal week according to these records," Ms McEvitt said.
Mr Kennedy asked specifically about August 22, 2012, the day the prosecution claims he murdered Ms O'Hara.
"According to records he started work at 8.30am and worked a normal eight-hour day," she said.
She agreed there was no record of him leaving the office early either on August 22 or 23, 2012.
Ms McEvitt also told Mr Justice Tony Hunt that each employee was emailed blank timesheets and each had a role in filling them in and returning them to her.
A director of A&D Wejchert, David Lanigan, gave evidence that Mr Dwyer had been involved in a range of projects and areas within the practice but was particularly skilled in 3D visualisation and artist's impressions of projects and presentations.
"Mr Dwyer had a number of different cars over the years," he said, recalling that he once owned a Porsche and four-wheel drive.
Mr Lanigan told the court Mr Dwyer was very skilled with computers and had an office desktop, smart phone, laptop and a notebook and stored information on USB keys.
While he was based in the office on Lower Baggot Street, he also worked on projects around Ireland and in Poland, where the founding partners were from.
Mr Lanigan said Mr Dwyer would "typically" leave the office at around 4.45pm each evening to let his childminder go, adding that partners would usually tell reception if they were going out.
However, there were times during the day when they could go out at short notice so occasionally reception was not told.
Mr Guerin took Mr Lanigan through a series of dates to confirm if Mr Dwyer attended board meetings in the office, site meetings and evening events, including events held by the Irish Polish Business Association in the Polish Embassy and seminars organised by Enterprise Ireland.
He agreed there was an error in the office records on December 2, 2011, which recorded Mr Dwyer being in Poland. Mr Lanigan agreed Mr Dwyer had been working on a project at Leopardstown Racecourse in August 2012.