Giving evidence at her Newry Crown Court trial, 23-year-old Lindsay White denied any involvement in the July 2009 murder of 40-year-old Marek Mateusz Muszynski.
She maintained that she tried to stop 20-year-old Adrian Gregory Cunningham, from jumping on him "like a trampoline".
Cunningham, from Lisgullion Park, Newry is already serving life for the murder Mr Muszynski, whose battered body was found in an alleyway, his trousers down around his ankles, and robbed of his last 70p.
In his evidence, Cunningham claimed that White, from Mary Street, Newry, not only helped kick and stomp on a defenceless Mr Muszynski, but instigated the attack.
He also claimed that it was she who later robbed him of the few pence he had, before they both went off to get more drink and a Chinese take-away.
However, on Thursday, an often emotional White told her defence QC Turlough Montague that the Pole was "a decent enough person" and the more she'd shouted at Cunningham to stop his attack "the harder" he hit out.
White also maintained that afterwards she only went on with Cunningham, who said he needed a drink, and later asked her to buy him a Chinese because he was hungry, out of fear of what he might do to her.
Asked what she thought of Cunningham now, she replied: "To me he was a monster, that he would do that to a human being".
White also claimed that after the attack Cunningham "looked like a different person ... he seem proud of what he had done ...as if he had to prove something".
Describing herself as "a coward" for not doing more to help or even call Mr Muszynski an ambulance or the police, White said she was scared of Cunningham who was playing mind games with her because he knew she was mentally unwell.
At one stage Cunningham even suggested that they were in the clear because others, including a girl, had been arrested for the murder.
White said that when returned to Northern Ireland, following her arrest in London, she claimed "from day one" she told police the truth because she wanted "justice" for Mr Muszynski family.
"I was upset," said White, who added she thought Cunningham, "was trying to frame me .....I told the truth from day one because I wanted justice for his family".
Earlier she admitted to the court that she too had punched Mr Muszynski in the face before the main attack, but claimed she'd reacted in self-defence when she felt intimidated by him when he came at her.
"He said, no, no, no, and said he wasn't going to hurt me and gave me a hug".
However, she claimed that Cunningham, who'd accused the Polish man of "stealing from old ladies" as they walked down the entry, punched him four times in the face, knocking him to the ground.
He then began kicking him in the side of the head several times before he then began to stomp on his throat.
White, who said she was shouting for him to stop, also said that she could hear Mr Muszynski's head "hitting the floor ... the concrete ... bouncing off the stones" and saw Cunningham "jump on his stomach as if it was a trampoline".
Later, she told Mr Montague that while she saw blood on Cunningham's shoes, she had none on hers "because I did not attack the man".
She also denied washing her jeans afterwards because she "did not have a washing machine at that time".
Asked pointed if she'd attacked Mr Muszynski or stomped on his throat, White replied ,"No" each time.
When asked if she'd struck him after her initial punch, she said: "No, because he gave me a hug and I thought he was a decent enough person".
Later under cross-examination by Mr Philip Mateer QC, White rejected suggestions that she was "telling lies" and that she "didn't phone for an ambulance because you didn't give a damn about him ....you didn't care for him ...then afterwards walked the streets of Newry totally unconcerned".
White maintained at all times she was running scared of Cunningham and "didn't know what to do ... I didn't think straight" admitting she "was a coward...I didn't know what to do .....but I didn't touch that man".
At one stage she said she felt as if she were going through a nervous breakdown, and that Cunninghman was "hounding and hounding and hounding me".
White also claimed that her former co-accused "was playing on my mental health issues .... he was very clever".
Submissions are expected to start on Friday before Judge David McFarland gives the jury of eight men and three women their final instructions on Monday prior to sending them out to deliberate on their verdict.