Cynthia Vanier's father John MacDonald said Wednesday the family had been told that her detention will be extended even though no charges have yet been laid.
"They're not in a position to lay charges yet, they're still investigating, so she stays where she is," he said in a telephone interview.
MacDonald said he and his wife have spoken to Vanier on the telephone half a dozen times since the arrest and will be flying down to Mexico to visit her after Christmas, but they are worried about her health issues, including high blood pressure.
"Her blood pressure was 180 over 90, she's seen a doctor, she has some kidney problems," he said.
"They're supposedly getting some medication for her, but they've notified us that where she is now has been extended up to (another) 40 days."
Vanier has been held in Mexico since Nov. 10.
John Babcock, a spokesman for Diane Ablonczy, Minister of State of Foreign Affairs, said the Canadian government was aware of the detention and providing consular assistance to Vanier and her family.
"Our officials at the Embassy of Canada in Mexico City are in contact with local authorities and are closely monitoring the situation," he said in an email.
But MacDonald said it's been frustrating trying to find out information about what will happen next and wishes the Canadian government would do more to help.
"They say there isn't too much they can do, but you'd think they can do a little more than what they do," he said.
Vanier, a mediator based in Mount Forest, Ont., is accused by Mexican authorities of planning to illegally smuggle the late Libyan dictator's son Al-Saadi Gadhafi into Mexico.
Mexico's interior minister has accused Vanier of masterminding a plot to bring Gadhafi to Mexico, which allegedly also involved two Mexicans and a Danish suspect, all of whom have been detained.
Gadhafi denied last week he was trying to enter Mexico. He fled Libya earlier this year after the fall of his father's regime and was given refugee status in Niger.
Vanier denies the allegations and her parents say they believe she is being used as a scapegoat.
Officials in Mexico couldn't confirm the extension, but noted that under Mexican law, it is standard practice to detain suspects in relation to federal charges so that police are able to gather all the information and evidence needed to bring charges, should they apply.
The decision to detain a suspect as a cautionary measure is made by a judge, at the request of federal prosecutors.
They also note Vanier is not being held in a federal prison but rather a detention centre, where she is under supervision but can have daily visits from family or her lawyers and has access to medical care.
Vanier's Canadian lawyer Paul Copeland said he was still trying to find out the details of the latest decision and whether there can be a second extension to Vanier's detention before any charges are laid.