A Franco-Cameroonian man met his family for the first time in 17 years at Paris's Charles de Gaulle airport after being released from jail in Cameroon this week.
Michel Thierry Atangana served his sentence in isolation in a cell in which he could not even stand up straight, his lawyers said.
Describing himself as "worn out" by his jail time, Atangana told reporters that he had suffered a "shock that you can't imagine" and that now he had to "find himself".
"He was in isolation in a room that was too small for him," said one of his lawyers, Eric Dupond-Moretti. "He couldn't stand up, literally or figuratively, and that ordeal lasted 17 years.
On arrival, Atangana spent some time alone with his family in a room at the airport.
"I'm practically seeing him forthe first time in my life today," said his 23-year-old son Eric, who was six when his father was arrested.
Atangana was to go to the Val-de-Grâce military hospital for a medical checkup.
The 49-year-old, who obtained French citizenship at the time of his marriage, was freed this week by a decree by President Paul Biya that ordered the release of anyone serving over 10 years for embezzling public fund, the crime for which Atangana was jailed for 15 years in 1997 and a further 20 in 2012.
He claims that he was politically victimised and is reported to have been close to a former Biya ally, Titus Edzoa, who was arrested shortly before him after coming out in opposition to the president. Edzoa was released on Monday, as was Atangana.
Last year President François Hollande declared the amount of time Atangana had spent in jail "unacceptable".
In December his lawyers brought cases against three Cameroonian ministers for "arbitrary detention".