A Facebook video, now authenticated by the human-rights group Amnesty International, shows malnourished captives -- most thought to be Somalis -- crammed into concrete cells.
Some are forced to contact family members and describe their unimaginable torture.
Other times, it is the captors, criminals who have seized control in lawless regions of Libya, demanding money.
A leader in Melbourne's Somali community, Aden Ibrahim, says the ransom is generally around $8,000 US, equivalent to more than $10,000 Australian.
"This a lawless place, so, once the person has been called and if the person hasn't paid the ransom money in time, that person may be used as body parts or, worse, may be shot dead -- killed or, basically, mutilated."
Mr Ibrahim has a confronting collection of photographs provided by Australian-based Somalis who have been contacted by captured relatives or the criminals themselves.
He says the captors' demands are grim.
"They actually call you to tell you only a few bones have been broken but the person's still alive and, if you don't pay, they'll be finished."
Not even paying the ransom guarantees release, though, and there is no single government in Libya for authorities to lobby.
The director of Human Rights Watch Australia, Elaine Pearson, says it is time authorities and governments consider how they can intervene.
"There's been a complete breakdown of law and order in the country. There's no justice system, to speak of. So, in that vacuum, it's allowed criminal groups to act with impunity."
Mr Ibrahim is urging all African-Australians to warn any relatives considering passage through Libya.
"They have to be a little bit more vigilant, and, instead of hearing their loved ones are in a camp in Libya, they should advise them before they go."
