OTTAWA - The family of a Canadian pastor serving a life sentence in North Korea is concerned for his welfare after the death of an American student after imprisonment there, and wants Canada to work harder to secure his release, a spokeswoman said on Wednesday.Hyeon Soo Lim, who served at one of the largest churches in Canada, was sentenced to hard labor for life in December 2015 for what North Korea says was an attempt to overthrow the regime.Family spokeswoman Lisa Pak said Lim's family wants to see a more aggressive approach from the Canadian government following the death of American university student Otto Warmbier earlier this week, days after he was released from captivity in North Korea in a coma."The family is very concerned at this point," said Pak. "They are hoping the Canadian government will turn (efforts) up a few notches in terms of active diplomacy and really start engaging."Pak said there have been no substantial developments in the case since December 2016 when Canadian officials visited Lim.The family spoke with Canadian officials this week, who promised something different would be done, though they did not provide details, she said.While a lower-key approach had seemed appropriate given the sensitive nature of the situation, Warmbier's death has changed that, Pak said."The countries who have detainees in North Korea have an option now and they really need to take full advantage of it to get the other people who are still alive back home to their families."In addition to Canada's Lim, North Korea is holding three Americans.A spokeswoman for Global Affairs Canada, the government's foreign affairs department, said the case is "absolutely a priority.""The government of Canada is very concerned about the health, well-being, and continued detention of Mr. Lim," spokeswoman Jocelyn Sweet said."We have been actively engaged on this difficult case and consular officials are working actively to secure Mr. Lim's release."The Swedish ambassador visited Lim earlier this year and told the family he was in decent health at the time, Pak said.Lim's Toronto-area church has said Lim visited North Korea more than 100 times since 1997 and helped set up an orphanage and nursing home.Last year, Lim told CNN he spends eight hours a day digging holes at a labor camp where he has not seen any other prisoners.