A Canadian man is suing the country’s government after he was arrested by border agents and detained for eight months – despite producing evidence of his citizenship.

Olajide Ogunye, 47, is seeking $10m in compensation from the Canadian government after he spent months incarcerated in what his lawyer has described as a “profoundly disturbing” case of mistaken identity.

Ogunye was approached by border agents and detained outside his Toronto home in June 2016, even though he produced citizenship papers and a government-issued health card.

The agents disputed the validity of the documents and brought him to a detention facility near Toronto Pearson airport, where they fingerprinted him and alleged his prints matched those of a fraudulent refugee claimant who was deported to Nigeria in the 1990s.

“It is shocking,” said Adam Hummel, Ogunye’s lawyer. “Even people who are having their citizenship revoked … are not detained like this.”

The results of the fingerprint analysis – which Hummel says were never shown to his client – were contradicted by numerous sworn affidavits by friends and neighbours who had known Ogunye for years.

Ogunye, who immigrated to Canada from Nigeria with his family and became a citizen in 1996, was moved between Maplehurst correctional facility and Central East correctional centre.

Near-constant security lockdowns – a problem plaguing prisons and jails throughout the country – prevented him from making contact with family members. Traumatized by his detention, he was placed on suicide watch.

“One time, for the whole month, I was crying nonstop. I was crying continuously,” he told the CBC. “The nurse had to give me depression pills to make me calm down.”

Ogunye was released in February 2017. Canada Border Services Agency (CBSA) alleged fraud and impersonation by Ogunye as justification for his detention.

CBSA said in a statement that it had received Ogunye’s claim and was reviewing the matter, but that it would be “inappropriate” to comment further.

Targeted arrests, like the one that ensnared Ogunye, are common for clearing a backlog of immigration violations, said a number of lawyers working in immigration and refugee law.

But the arrest of a Canadian citizen by border guards was nearly unheard of, said Max Chaudhary, a Toronto-based immigration lawyer. “That’s simply not what [border] officers do. Their mandate is not with Canadian citizens.”

Chaudhary speculated that if border officials believed Ogunye was a foreign national or permanent resident violating immigration laws, it could explain the duration of the detention – and the slow pace in which investigation unfolded.

“It seems quite incredible there could be a case of mistaken identity that could not have been cleared up in a faster amount of time, having this person deprived of his liberty for eight months,” he said.

Ogunye’s case was indicative of a broken system, said Lorne Waldman, a professor of immigration law at Osgoode Hall. Despite years of lobbying for oversight of the agency’s conduct – and assurances from the public safety minister, Ralph Gooddale, that such mechanisms would be put in place – Wadlman said no progress has been made

“Because there’s no oversight, there’s nobody who reviews the conduct of CBSA officers and this matter was allowed to drag on for months and months. It’s extremely unacceptable.”

Hummel and his client charge that the government breached Ogunye’s constitutional rights; he filed the case in Ontario superior court on 30 May.

“The very fact that this happened, someone who was approached and showed he was a Canadian citizen, means that it could happen to anyone if this is how [border agents] are operating,” he said.