Amnesty International wants to see the Sorcery Act repealed.
"Sorcery is a real belief held by Papua New Guineans and I don't refute that," said Schuetze.
"But what we're saying is that this type of violence is never acceptable and cannot be excused regardless of what your cultural beliefs are."
Schuetze said sorcery is often used as pretext to commit violence against women, who are six times more likely to be accused of witchcraft than men.
"We also heard when we were on mission last month that if a person accuses a woman of sorcery, they can do anything against them and no one will intervene to stop it."
Police, who face ongoing capacity issues, also find themselves unable to intervene when faced with large lynch mobs - meaning the fight needs to go to a higher level, she said.
"The [Papua New Guinea] government needs to send a clear message to the people that this type of violence will not be tolerated and anyone accused ... including murder, will be punished like any other person under the criminal code."
And New Zealand, which has a strong history of ties with Pacific Island nations, can help.
"[New Zealand] plays a good role in supporting Pacific Island countries to look into and reform so that they're in line with international human rights framework.
"So we would be calling on the New Zealand Government to use their diplomatic channels to raise this issue and encourage the Papua New Guinea government to repeal the Sorcery Act and increase protections to end violence against women."
- nzherald.co.nz