Suzanne Breen received the admission of responsibility for two murders
A judge is expected to rule early next week on whether a police application to force a Belfast journalist to hand over material can be heard in private.
The PSNI is trying to force Suzanne Breen to hand over material linked to two Real IRA articles.
She had been given seven days to comply but refused saying her life could be in danger if she were to agree to the PSNI's request.
Ms Breen is the northern editor of the Sunday Tribune.
On Friday, a High Court judge heard evidence under oath from a police officer.
Ms Breen received the Real IRA's claim of responsibility for the murder of two soldiers at Massereene barracks in March.
Sappers Mark Quinsey, 23, from Birmingham, and Patrick Azimkar, 21, from London, were shot dead as they collected pizzas outside the County Antrim base in Antrim on 7 March.
Police said they would use all possible legal means "to access information which may assist their inquiries".
Former Sunday Tribune journalist Ed Moloney, who successfully resisted police attempts to get him to hand over notes in the 1990s, said there were important principles at stake.
"It's not the job of journalism to do police work," he said.
"Let the police pursue those who they think gave Suzanne Breen those interviews.
"That's just a cast-iron rule, and I don't think we should bend from that."