His partner called 111 and the first police officers to arrive tried to save his life but the injuries were too severe.
Tulua had four children from a previous relationship who did not live with him, but he had spoken to them on the phone shortly before he was gunned down.
Local residents woke on Easter Sunday to see an armed police guard on the street as a homicide investigation was launched.
Richards said although police had charged two people with the murder of Tulua, they still wanted to hear from people who had information relating to the investigation.
"Even four months after Mr Tulua was shot and killed, our detectives continue to piece together the events surrounding his death," Richards said.
"We appreciate the information police have received so far which has ultimately resulted with the two people now before the court."
Police ask anyone with any information in relation to this matter to contact them on (09) 2611 321 or anonymously via Crimestoppers on 0800 555 111.