Police in Papua New Guinea have boosted the number of officers on Karkar Island in Madang Province to investigate the gang rape of a US academic by an armed mob last Friday.
The female victim was on the island for research with an expatriate male companion and a male PNG guide.
A spokesman for the police, Dominic Kakas, says the police have established that one of those involved in the attack is a prison escapee.
He says he hopes villagers can help the police.
"We are doing all we can to actually apprehend those involved. We will make sure that no one escapes from this and we will seek out the maximum punishment for this. Now as you are aware in PNG, our laws are such that rape carries a life imprisonment penalty."
Dominic Kakas says police are close to arresting offenders involved in an incident earlier this month in Mount Hagen where an Australian man was killed and a woman staying at his house sexually assaulted by a group of men.