The sister of one of the Greenpeace activists arrested in Russia over an oil-rig protest says his family is "cautiously optimistic" about the news charges against the so-called Arctic 30 are being dropped.

Paul Ruzycki of Port Colborne, Ont., was one of 28 Greenpeace activists and two journalists who were detained in September following a high-seas protest at the Prirazlomnaya oil rig in the Arctic, where several demonstrators attempted to scale the offshore drilling platform before they were intercepted and their ship was commandeered by Russian commandos.

The group was originally charged with piracy, but that was downgraded to hooliganism.

Russian investigators have now dropped charges against all but one of the Greenpeace ship's crew — including another Canadian — the environmental group said Wednesday.

Ruzycki's sister, Patti Ruzycki-Stirling, told CBC News she's not taking anything for granted until her brother is on a plane home to Canada.

"We have had these kind of rumours over and over again — 'it's over, they're coming home, it's over' — and then suddenly everything goes into a tailspin and everything stalls," she said.

"I mean it looks really positive this time, but as I said we're cautiously optimistic."

One of the Greenpeace 30, Cristian d'Alessandro of Italy, failed to get his criminal case closed due to the lack of an interpreter and will have to visit the St.Petersburg branch of Russia's Investigative Committee again on Thursday, Violetta Ryabko, a Greenpeace spokeswoman, said.

Ruzycki and Alexandre Paul, from Montreal, were among those who had their charges dropped.

Amnesty

The criminal charges against the crew were dropped under an amnesty that was passed by the Russian parliament earlier this month, seen by many as an attempt by the Kremlin to dampen criticism of Russia's human rights record before the Winter Olympics in Sochi in February.

"This is all PR on Putin's part trying to look good before the world comes to Russia," Ruzycki-Stirling said.

Ryabko said that foreign members of the crew had already applied to the Russian authorities for exit visas to leave Russia and expect to get them in the next few days.

The 30 crew members aboard the Greenpeace ship Arctic Sunrise were held in custody for two months before they were released on bail in November.

Peter Willcox, the U.S. captain of the Greenpeace ship Arctic Sunrise, said in a statement released by the group that he was "pleased and relieved the charges have been dropped, but we should not have been charged at all."

Russian President Vladimir Putin has questioned the Greenpeace protesters intentions to protect the Arctic and alleged that they were trying to hurt Russia's economic interests by demonstrating at the oil rig, run by state-controlled petroleum company Gazprom. He said earlier this month that he did not mind that charges against the Greenpeace team were dropped under the amnesty, but that he hoped that "this will not happen again."

Greenpeace says Gazprom — the world's largest gas company — risks causing a catastrophic oil spill in an area with three nature reserves that are home to polar bears, walruses and rare seabirds.

Gazprom says it began production from the Prirazlomnaya offshore platform this week.

Greenpeace argues that any oil leak would be catastrophic in the pristine environment and impossible to bring under control.