THE sister of convicted killer Daniel Martin has refuted claims she altered her story to cover her brother's back.

Sarah Martin told a court today she "would not alibi her brother" when she's the mother to three children.

Earlier this year, Daniel Martin admitted the manslaughter of 52-year-old Andrew Heath who was found dead following an arson attack at his flat in Chedworth Close, Warndon, Worcester in the early hours of December 14, 2011.

Sarah, her mother Teresa Martin, and Sarah's partner Matthew Davies are currently facing trial at Birmingham Crown Court charged with perverting the course of justice in relation to the investigation.

Giving evidence, Sarah Martin was accused of tailoring her version of events by saying she woke her brother up to go and look at the aftermath of the fire.

The court was told that her mother, who lived with Daniel Martin in Rodborough Close, Warndon, wanted Sarah to keep an eye on him as she believed he was using cocaine.

"I was being nosey and went out in the street," said Sarah Martin, having been woken by the commotion outside Mr Heath's nearby flat around 5.30am that morning.

"A lot of people were out there that morning.

"Matt (her partner) always moans at me for being a gossip. I knew he would not be interested (in going outside to see what was happening).

"But I thought Danny would want to know."

In police interview she said she thought she would pop round to check on Danny at that time instead of going during the school run.

She says she left her Rodborough Drive home to wake her brother, a point queried under cross examination.

"There is no need to take him out into the street is there," said prosecutor Gareth Evans.

"What is the need to wake him?

"In truth, you didn't go and wake up Danny, because he was already out.

"You are doing your best to help him.

"And why didn't you call your mum at work to tell her Danny was ok?"

She replied saying her mum would have got into trouble for using her phone at work.

"If he was really ill I would have called her. But because he was ok, I didn't see the need.

"She was ringing me at 7am anyway so I would tell her then.

"And I would not alibi my brother.

"My children always come first. Why would I lie?"

No motive for the attack has ever been disclosed and Daniel Martin is expected to be sentenced at a later date.

Earlier in the case, Mr Evans said Teresa Martin claimed her son was at her home until at least 4.30am on the morning of the fire.

But Mr Evans said it is accepted the fire was lit by Daniel Martin at 3.30am.

The jury is expected to retire tomorrow.