A Russian judge has said that one of five suspects in the murder of opposition activist Boris Nemtsov had confessed to his involvement, state media reported.
Four others pleaded innocent in a court in Moscow.
Judge Nataliya Mushnikova said Zaur Dadayev had signed a confession stating his involvement in the crime.
She ordered his detention be extended until 28 April.
"The participation of Dadayev is confirmed by his confession," she told the court.
Dadayev, a former deputy commander for the Chechen police, and Anzor Gubashev, who worked for a private security company in Moscow, were arrested yesterday in the republic of Ingushetia, which neighbours Chechnya in the volatile northern Caucasus.
They were both charged with murder, however Mr Gubashev denied his involvement.
Three other suspects, who have not been charged, claimed they were innocent. However, a representative for the investigation told the court there was "proof of their involvement".
They were named as Shagid Gubashev, Anzor's younger brother, Ramsat Bakhayev and Tamerlan Eskerkhanov.
The suspects were detained a little over a week after Mr Nemtsov, a long-time critic of Russian President Vladimir Putin, was shot four times in the back as he strolled with his girlfriend along a bridge in full view of the Kremlin and Red Square.
The murder of Mr Nemtsov, a 55-year-old former deputy prime minister, was the most high-profile killing of an opposition figure in the 15 years that Mr Putin has been in office.
Some associates of Mr Nemtsov say the Kremlin stands to gain from his death.
Russian officials deny involvement and Mr Putin has condemned the killing.
Today's court hearings were given extensive coverage on state-controlled media, and presented as proof the authorities are conducting a thorough investigation - not the cover-up some of Mr Nemtsov's friends say they anticipate.
But associates of Mr Nemtsov say they will not be satisfied unless prosecutors track down whoever orchestrated the killing, rather than just the people who pulled the trigger.
There was no word from investigators on who the suspects were alleged to have been working for.
The judge presiding over the hearings said investigators were still looking for others they believe were involved in the killing.
Several other high-profile killings in Russia, including the 2006 shooting of journalist Anna Politkovskaya, have been attributed to gunmen from the North Caucasus, while those who ordered the crimes were never firmly identified.
