Afghanistan's main intelligence agency announced on Wednesday that it had arrested a commander suspected of involvement in the murder of Sveriges Radio correspondent Nils Horner.
The suspect is said to belong to Afghan militant group Mahaz-e-Fedaiyan, loosely translated to Suicide Front, which previously took responsibility for the crime.
"The [Afghan] National Directorate of Security detained a militant commander of the terrorist group Mahaz-e-Fedaiyan ... with two pistols, two grenades and a silencer," Hassib Sediqi, a spokesman for the agency, told the Reuters news agency on Wednesday.
Horner, 51, who worked for Sverige Radio (Radio Sweden), took a fatal shot to the head in the Afghan capital's diplomatic quarters on March 11th 2014.
The attack occurred in broad daylight on a street in central Kabul while he was in the process of reporting for Ekot, a Sverige Radio news program, before last year's presidential election in Afghanistan.
Barely two weeks after Horner's murder, his collaborator, prominent Afghan journalist Sardar Ahmad, was also shot death.
Horner was a dual Swedish-British citizen.
Information about the arrest was forwarded to Swedish authorities on Wednesday.
"The investigation in Sweden is still ongoing," Anders Skiöldebrand at the Swedish Embassy in Kabul told Reuters.
"The [Afghan intelligence] information has reached us, but we cannot comment on our next steps at this time," the prosecutor in Horner's case in Sweden Krister Petersson told SVT, Sweden's national news broadcaster.
"We have an open investigation that we are working on continuously, but I do not want to comment further as it could hamper the investigation," he added.
Ekot's director Anne Lagercrantz told the TT newswire that she thinks it is too soon to celebrate with so many questions still left unanswered.
"We certainly hope that those responsible are brought to justice, but this latest information is still very uncertain," she said.
The information about the arrest came as a surprise even for the Swedish Embassy in Kabul, according to Sweden Foreign Ministry communications officer Charlotta Ozaki Macías.
She said that it was still unclear how linked the group's commander's arrest is to Horner's murder case.
"The [Swedish] Embassy is investigating to get the full picture," she told TT.
Mahaz-e-Fedaiyan members define themselves as defectors from the Afghan Taliban movement, and the group is officially labelled a terrorist organization by the Afghan government.
The group has also claimed responsibility for the murder of Arsalah Jamal, the late governor of the eastern Afghan province Logar, in Autumn 2013 as he was delivering a speech to mark the Muslim holiday of Eid al-Adha.
According to a statement on the group's website and Facebook page last year, the Swedish radio journalist was murdered because he was an "agent for M16", referring to Britain's official intelligence agency (SIS).
The group's leader, Haji Najibullah, is also believed to be responsible for the kidnapping in 2008 of New York Times journalist David Rohde.