(Reuters) - Ukraine said on Friday it was investigating the death in Russian captivity of a Ukrainian journalist whose first-hand reports provided a glimpse into life under Russian occupation early in Moscow's invasion.

Viktoria Roshchyna, 27, disappeared in August 2023 after embarking on a reporting trip to occupied eastern Ukraine, and Russia acknowledged last April that she was being held.

Ukrainian human rights ombudsman Dmytro Lubinets confirmed her death on social media late on Thursday in what he condemned as illegal detention. He did not specify the circumstances.

Andriy Yusov, a spokesperson for Ukraine's military intelligence, told the public broadcaster Suspilne that Roshchyna had been on a list of prisoners to be exchanged, and that "everything necessary had been done" for the swap.

She had been due to be transferred to Moscow from the southern city of Taganrog, he said.

The campaign group Reporters Without Borders said Roshchyna had died on Sept. 19, citing a letter that her family received on Thursday from Russia's Defence Ministry.

The Ukrainian Prosecutor General's office said it had updated its war-crime investigation into Roshchyna's disappearance to include murder.

By Friday morning, Russia had not publicly commented on her death.

"What did they do with her? What could have been done to a young girl to make her die?" activist and colleague Oleksandra Matviichuk, a 2022 Nobel Peace Prize laureate, wrote on X.

REPORTER DOCUMENTED LIFE UNDER RUSSIAN OCCUPATION

Roshchyna's vivid reports documented Moscow's efforts to cement Russian power in parts of occupied eastern and southern Ukraine after the Kremlin's invasion in February 2022.

She also captured the difficulty of daily life in the Black Sea peninsula of Crimea, which Russia seized and unilaterally annexed from Ukraine in 2014.

Roshchyna's articles for outlets such as Ukrainska Pravda and U.S.-funded Radio Liberty included photographs of Russian military hardware and revealed the extent of ruin in Mariupol, the southeastern port city devastated by a months-long Russian assault and siege.

She had been held once before by Russian forces, for 10 days, in southeastern Ukraine in the first weeks of the Kremlin's invasion.

Ukrainska Pravda editor-in-chief Sevgil Musaieva described Roshchyna as "incredibly brave" and committed to revealing the plight of residents under Russian occupation.

"It was impossible to stop her, to hold her back. She was completely dedicated to journalism," Musaieva wrote on Facebook.

In a statement, the Committee to Protect Journalists blamed Russian authorities for Roshchyna's death and called on both Russia and Ukraine to investigate her death further.



(Additional reporting by Ron Popeski; Editing by Kevin Liffey)