Querol said initial investigation revealed that the victim, Oliver Ong-Dy, may have personally known his killers.
He said he has directed Muntinlupa police chief Senior Superintendent Roberto Rongavilla to gather all witnesses and evidence to identify the suspects.
Querol issued the order a day after Philippine National Police (PNP) chief Director General Arturo Lomibao called for an immediate investigation into the killing.
Lomibao had called on Deputy Director General Oscar Calderon, chief of the Police Anti-Crime and Emergency Response (PACER), to verify reports about the killing of Dy, who was abducted in Muntinlupa City last Aug. 14.
The National Bureau of Investigation (NBI) also declared it would help track down Dy’s killers.
NBI—Metro Manila director Edmund Arugay said they would extend help to the PACER and Muntinlupa City police in tracking down suspects.
Text messages had circulated saying that the father of the victim, Manuel Dy, a ranking official of the Federation of Filipino-Chinese Association in the Philippines, had revealed to a Chinese newspaper what happened to his son.
The story was published in the Chinese newspapers United Daily News and World News.
The Dy slaying added to criticism that President Arroyo was not doing enough to solve recent kidnapping cases in Metro Manila.
There were even claims that Malacañang had imposed a news blackout on the Dy case.
Without going into details on the reported kidnap-slaying, Lomibao cleared the President of the allegations of a cover-up.
Querol added some sectors might be using the Dy slay case to discredit the President.
"You must solve the case in a week. You see to it that you get the killer and hail him to court," Querol told Rongavilla over the telephone.
"The local police are focusing manpower and other resources on solving the case to end speculations being spread by the political enemies of President Arroyo," Querol said.
The Muntinlupa City police earlier declared they were already closing in on the killers of Dy.
The 35-year-old Dy was found dead on Olympus street at the Camella E-2 Subdivision in Barangay Putatan with multiple stab wounds.
Police said the murder weapon, a screwdriver, was found at the crime scene.
Investigator Senior Police Officer 2 Cristito Veluz said the killers initially knocked Dy over the head with a rock before stabbing him.
He said the killers sped off in the victim’s Chevrolet, with license plate XWL-583, along with his belongings.
Dy was last seen two days earlier, leaving his home in his car.
The family told police that Dy even sent a text message a few days before his disappearance informing them that he had spent the night with friends. It was the family’s last contact with the victim.
The Dys initially feared that it was a kidnap case. But the police discounted the possibility after they failed to receive a ransom demand.
Querol also dismissed kidnapping as the possible motive of the killing. "It was a simple crime of passion," he concluded.
The PNP also ruled out kidnapping as the possible motive, national police spokesman Chief Superintendent Leopoldo Bataoil said.
"It was a case of a stabbing incident (and) murder case being investigated by the PNP. We have good leads and we are confident we will be able to solve this case soon," Bataoil said. — With Evelyn Macairan, Cecille Suerte Felipe