COPENHAGEN, Denmark (AP) — Two Iranian-born Swedish brothers were given lengthy prison sentences on Thursday for spying for Russia and its military intelligence service GRU for a decade in the Scandinavian country’s biggest espionage case in decades.

The oldest of the two naturalized Swedes — Peyman Kia — was sentenced to life, while his younger brother, Payam Kia, was sentence to nine years and 10 months. They had appeared before the Stockholm District Court where they faced charges of having worked jointly to pass information to Russia between Sept. 28, 2011, and Sept. 20, 2021.

A life sentence in Sweden generally means a minimum of 20 to 25 years in prison. Anton Strand, the attorney of Peyman Kia, said his client would appeal the sentence, while the younger brother’s lawyer, Björn Sandin, said it hadn’t been decided yet whether to appeal.

“It is placed beyond reasonable doubt that the brothers, together and in consultation, without authorization and for the benefit of Russia and the GRU, acquired, forwarded and disclosed information” to a foreign power with the purpose of damaging Sweden’s security, the court said in its verdict.

The Stockholm District Court said that Payam Kia “was the driving force in their joint crime” while the involvement of Peyman Kia “was of lesser relative importance.”

The older brother had a “full understanding of the damaging effects — he has acquired, forwarded and disclosed the information to Russia, which constitutes the main threat to Sweden’s security,” the court wrote to explain the life sentence.

“After the district court’s evaluation of the evidence, it is clear that certain pieces of the puzzle are missing and that it has therefore not been possible to reach full certainty as to what happened,” Chief Judge Måns Wigén said. But “the picture of what happened is sufficiently clear for the defendants to be held responsible,” Wigén said. The motive was money.

As to the scope of the crime, Peyman Kia acquired about 90 documents while Payam Kia got approximately 65 documents, Wigén said.

“A disclosure of these documents could particularly damage Sweden’s security,” he told a news conference.

They “have been convicted of very serious crimes against Sweden’s intelligence and security system,” said Per Lindqvist, chief public prosecutor at the National Security Unit.

Throughout the trial that was held behind closed doors , both men denied any wrongdoing. Much of the evidence presented and material from the preliminary investigation is secret.

Between 2014 and 2015, Peyman Kia, 42, worked for Sweden’s domestic intelligence agency, but also for the country’s armed forces. Swedish prosecutors allege that the data they gave the Russians originated from several authorities within the Swedish security and intelligence service, known by its acronym SAPO.

Peyman Kia reportedly has worked for the armed forces’ foreign defense intelligence agency, known in Sweden by its acronym MUST, and worked with a top secret unit within the agency that dealt with Swedish spies abroad, according to Swedish media.

Peyman Kia was arrested in September 2021 and his brother in November 2021. Both denied any wrongdoing, their defense lawyers told the court.

Payam Kia, 35, helped his brother and “dismantled and broke a hard drive which was later found in a trash can” when his brother was arrested, according to the charge sheet obtained by The Associated Press.

In 2017, a preliminary investigation was launched after SAPO had become suspicious of the former employee and suspected there was a mole within Sweden’s intelligence community.

The case is believed to be one of most damaging instances of espionage in Sweden’s history, because the men had compiled a list of all the employees within SAPO.

One of Sweden’s largest spy scandals took place during the Cold War when Stig Bergling, a Swedish security officer who worked for both SAPO and the armed forces, sold secrets to the Soviet Union. He was sentenced in 1979 to life imprisonment on similar charges and later escaped while serving his time, and returned voluntarily to Sweden in 1994. He died in his native country in January 2015.