Pakistani police say there is no evidence to back claims that alleged 11 September mastermind, Khalid Sheikh Mohammed, killed Wall Street Journal reporter Daniel Pearl.
Four people have been convicted in connection with Pearl's murder
The Journal said on Tuesday that US officials now believed Sheikh Mohammed was directly involved.
But police in Karachi said they had thoroughly investigated the case and found no reference to the involvement of Sheikh Mohammed, who was captured in March.
Mr Pearl was abducted in Karachi and subsequently found dead in 2002.
British-born Islamic militant Ahmed Omar Saeed Sheikh was convicted last year by a Pakistani court of involvement in Pearl's kidnapping and murder, and sentenced to death.
Three accomplices were given life imprisonment. All four are appealing against their sentences.
Inspector general of police for Sindh Province, Kamal Shah, said they were not aware of developments concerning the Journal's claims.
"If the American Government sends any communication to the Pakistani authorities about this matter then we will look into it," he said.
The Journal said US officials had developed "credible, corroborated information" that Sheikh Mohammed had killed Mr Pearl.
Since his arrest in the Pakistani city of Rawalpindi this year, Sheikh Mohammed has been held at an undisclosed location and interrogated by CIA officials.
He is suspected of being the chief planner of the 2001 attacks on the World Trade Center and the Pentagon.
He is also accused of plotting to blow up several American airliners flying from south-east Asia to the United States in January 1995.
Mr Pearl, the Wall Street Journal's South Asia bureau chief, disappeared in January 2002 while researching a story about Islamic extremists.
A gruesome videotape of Mr Pearl's murder was later sent to US officials and his body was discovered the following May.