The judge in the trial of Croydon police station killer Louis De Zoysa refused a defence request for jurors to visit and inspect the holding cell where he shot dead Sergeant Matt Ratana.
Lawyers acting for the former HMRC data analyst made an eve-of-trial plea for jurors to travel more than 80 miles to south London to view the custody block where the 25-year-old claimed to have had an autistic meltdown.
The trial judge turned down the defence's request, which was covered by reporting restrictions until the end of the trial, after hearing that extensive photographic evidence would be shown to the jury, explaining the dimensions and lay-out of the custody area.
During legal arguments at Northampton Crown Court, defence KC Imran Khan said he had visited the scene of the killing - holding room two at the Windmill Road custody block - and his view was that it appeared smaller in real life than in wide-angle photographs.
Mr Khan told High Court judge Mr Justice Johnson: "We are dealing with a murder case with a potential life sentence."
The issue of whether De Zoysa had experienced an autistic meltdown while in police custody was "at the heart of the defence case", Mr Khan said.
The killer's KC added: "Mr De Zoysa appears to have acted instantly and impulsively.
"We have the ability for the jury to see the locus (crime scene)."
Inviting the judge to direct that four jurors at a time visit the first corridor De Zoysa was taken into, Mr Khan described it being "very dark" and "very threatening" and dimly illuminated.
"We would suggest. the door is closed behind them (jurors) and they experience it as the defendant did on the day," he said.
After suggesting that having his temperature tested by being "zapped" may have impacted De Zoysa's mental state, Mr Khan added: "We would invite the jurors to go into the cell four at a time. and sit on the bench.
"There is a sense of claustrophobia.
"I want to address the jury on that. This is how the defendant felt on that day."
But despite Mr Khan's submissions that a jury site visit would be incredibly helpful and "absolutely essential" for fairness, Mr Justice Johnson ruled that it was not necessary.