Neighbours heard Sydney woman Rachelle Yeo screaming that the man inside her unit would not let her open the door and begging for the police to be called, a court has been told.
Paul Darren Mulvihill is on trial in the NSW Supreme Court accused of murdering Ms Yeo, 31, in her North Curl Curl unit on Sydney's northern beaches on July 16, 2012.
He has pleaded not guilty, claiming he stabbed Ms Yeo, his former lover, in self-defence.
The Crown says the alleged murder followed Ms Yeo's decision to end a tumultuous affair between the two, which had begun in 2011 when they worked together at the Brisbane office of pharmaceutical company Sanofi-Aventis.
Hosanna Faletoese, who lived directly above Ms Yeo, said she heard a woman's screams and went downstairs to investigate. She knocked on the door several times and said, "Open the door."
When the screaming and banging noises continued, Ms Faletoese yelled that she would call the police if the door wasn't opened.
Ms Faletoese said she heard a woman scream, "I can't open the door, he won't let me" and "Call the police."
She also heard a male voice call out, "You don't need to call the police, everything's OK."
Ms Faletoese's partner Peter Gualtieri said the woman sounded "very distressed, asking for help as loud as she could" but the man sounded "calm".
Another neighbour, Dianne Burrows, said she heard crashing sounds like furniture being thrown around and a woman who was "crying and very distressed".
Mr Gualtieri said after he got off the phone to triple-0 the noises stopped and "it went quiet".
Police arrived but were unable to break down the door with their boots so another neighbour brought them a hammer.
Ms Yeo was found inside with stab wounds.
The trial continues before Justice Elizabeth Fullerton.