Prosecutors claimed on Wednesday that Nikita Brogan emerged with spray and tissues following a knife attack on the man at their block of flats on Great James Street.
The 22-year-old aces a charge of assisting two offenders who are accused of wounding offences.
Police called to the scene found the alleged victim sitting on a sofa, covered in blood and being treated by paramedics.
The man claimed he had been attacked by two males who he did not know, but had been drinking with.
He was taken to hospital for treatment to a stab wound to his back which punctured a lung, a leg injury and facial slashes.
Crown lawyer Breige Gilmore said CCTV footage showed him approaching Brogan’s flat earlier that night with a hammer in his hand.
She contended that following an altercation he was pursued by the two co-accused.
One of them allegedly punched the man several times, while the other appears to repeatedly stab him as he tied to get into his own apartment.
Counsel claimed the footage then shows Brogan leaving her flat with a spray bottle and tissues or toilet roll.
“She is seen cleaning up the blood on the stairs and landing,” Ms Gilmore said.
During police interviews Brogan said she had been drinking when the complainant appeared at her door holding a hammer.
She claimed that she panicked and retreated inside, emerging five minutes later to see blood outside the man’s flat.
Ms Gilmore went on: “She said she wasn’t told to clean up the blood, she did it because it was messy and no other reason.”
Opposing her application for bail, the barrister told the court: “This applicant lives in the same complex as the victim, and he is viewed as a vulnerable adult.”
Defence counsel Richard McConkey argued that Gilmore’s alleged role in the incident was “peripheral”.
His client was not involved in any attempt at a forensic clean-up, Mr McConkey insisted.
With Brogan seeking to be released to live in Letterkenny, Co Donegal, Mrs Justice Keegan adjourned the application.
She gave the prosecution one week to consider a proposed address and monitoring arrangements with the Gardai in Letterkenny.