The trial, which is being held before a special anti-terrorism court convened at Karachi's Central Jail, remains closed to journalists and to the public.
Pakistani police have accused British-born militant Ahmed Omar Saeed Sheikh of masterminding Pearl's kidnapping. The three other defendants—Salman Saqib, Fahad Naseem, and Sheikh Mohammed Adeel—were allegedly involved in sending e-mail messages to news organizations announcing Pearl's abduction.
All four men have pleaded not guilty. Seven others accused in the case remain at large.
"We are watching developments in this case closely," said CPJ executive director Ann Cooper. "The government of Pakistan has pledged to do everything in its power to ensure that Daniel Pearl's killers are brought to justice. We hope that Pakistani officials will continue to pursue their investigations aggressively."
Pearl, 38, was apparently abducted on January 23 in the port city of Karachi while investigating a story about Islamic militants. On February 21, after receiving a videotape containing graphic evidence of Pearl's murder, U.S. government officials confirmed that he had been killed by his captors.
Pearl's body has not been recovered.
On March 14, a U.S. grand jury indicted Saeed on charges of hostage-taking and conspiracy to commit hostage-taking resulting in the murder of Daniel Pearl.
U.S. prosecutors also unsealed a secret indictment filed against Saeed in November 2001 accusing him of participation in the 1994 kidnapping of an American tourist in India.
Pakistani officials have so far resisted American requests for Saeed's extradition, arguing that justice should be done in Pakistan.
Among the witnesses who have testified so far is the taxi driver believed to be one of the last people to have seen Pearl alive, when he dropped the journalist off at the Metropole Hotel in Karachi on January 23. The taxi driver identified Saeed as the man who met Pearl outside the hotel and then took him away in a white car.
Today, two Karachi police officers testified that they were present at a February 14 preliminary hearing where Saeed admitted to kidnapping Pearl, according to a press briefing conducted by chief prosecutor Raja Quereshi after the court session. Defense attorneys argue that this testimony is inadmissible as evidence since Saeed's comments were not made under oath.