Video played for the jury in an arson trial shows the moment the Wangaratta home of an 81-year-old woman was engulfed in flames.
Police had placed a CCTV camera inside a house pointing back across the street, waiting for accused arsonist Lisa Hay to strike.
The 36-year-old lived at 114 Burke Street and has since pleaded guilty to lighting four fires at another neighbour's home at 116 Burke Street between April and July 2017.
The cameras were set up to catch her if she struck again.
But in the early hours of September 1, 2017, it was the house on the other side of Hay - 112 Burke Street - that was set on fire.
Hay has been charged with arson and reckless conduct endangering life, but has pleaded not guilty.
The prosecution has argued that because she lit the fires at 116 Burke Street, it showed she was responsible for the subsequent fire at 112 Burke Street.
The video played for the jury in Wodonga County Court on Monday showed a glow coming from the home of Catherine Sieger, which became bigger and brighter as flames took hold.
The prosecution also played the police interview between Detective Acting Sergeant Justin Schultz and Hay.
She told him she was a heavy sleeper and was asleep by 10pm the night before the fire, before her alarm woke her at 7.30am.
She said she did not hear fire trucks and police arrive at 2.30am to put out her neighbour's fire.
"I didn't know there was a fire there until this morning when the police officer told me to go back to my house because you wanted to talk to me," Hay said.
When told by Detective Schultz that she may be charged over the fire and asked if she wanted to say anything, Hay replied "nup".
A reflection on the CCTV video meant the view of Ms Sieger's house was obscured until 12.33am, when the fire appears to already be burning, before it dies down for a while then flares up again.
Detective Schultz said he could not say exactly when the fire started.
Triple zero was called at 2.27am.
Victoria Police fingerprint expert Robert Skvor told the court that three prints belonging to Hay were found on the fence between her and Ms Sieger's properties.
One was part of the palm of her left hand.
The other was a print from Hay's right pinky finger, which Mr Skvor said would most likely have been made by a "grip over the fence" from her property towards Ms Sieger's backyard.
The prosecution has alleged Hay jumped the fence before lighting the house on fire.
Under cross-examination from Hay's barrister Martin Kozlowski, Mr Skvor said the print could have also been caused by shaking the fence to see if it was rigid or grabbing it to look over, and fingerprints could potentially remain for years depending on environmental factors.
Hay told police in her interview that she had talked to Ms Siegel over the back fence four years earlier when she first moved in, but had never jumped the fence into her neighbour's backyard.
Mr Kozlowski said police never specifically asked Hay if she had touched the fence.
"She was never given the opportunity to explain why her fingerprints may have been found on the fence," he said.
Detective Schultz said a scarf found in Hay's front yard on the morning of the fire belonged to a witness who was first on the scene, not to Hay.
The trial continues on Tuesday.