Shane Mitchell, 23, initially told police he had returned to the house in Dalkeith, Midlothian, at 3.40pm.
But a few days later, he contacted a detective and admitted he had actually arrived back about 4.55pm.
The High Court in Edinburgh also heard that tests on Shane's computer revealed that porn websites had been accessed between 4.53pm and 5.16pm that day.
There were also 100 porn images stored on the computer.
Shane told Alan Turnbull, prosecuting, that he provided police with a 'very lengthy' statement three days after Jodi's death on June 30, 2003.
In it, he described what he did at home after arriving at 3.40pm.
But on July 7, Shane contacted the detective who had taken the first statement and changed his story.
He told the court: 'I wanted to make a second statement because there were errors in my first one.'
Shane said he was questioned by police on the day Luke was arrested last April. Officers told Shane they suspected he had deliberately given them false information.
Shane said he had visited Luke two or three times since he was arrested.
https://www.thefreelibrary.com/LUKE%27S+BROTHER+CHANGED+STORY+OF+DEATH+DAY%3B+Trial+hears+of+%27mistake%27.-a0126876476