Less than a year ago Ali Mohammed Moussa was slapped with an apprehended violence order meant to protect his former partner.

But in recent times, and allegedly without objection, the 43-year-old had been spending time with the woman and her daughter at their Lalor Park property in Sydney's west.

On Sunday night any prospects of reconciliation were thrown into inexplicable turmoil after the couple's little girl was shot dead.

A single-barrel sawn-off shotgun, allegedly brought onto the property and left unattended by Mr Moussa, caused the child's death.