MANILA, Philippines (UPDATED) - After he was dismissed from the police service, hostage-taker Rolando Mendoza snubbed three notices issued by the Philippine National Police (PNP) for him to return the M16 assault rifle issued to him.

Police spokesman Senior Superintendent Agrimero Cruz said the PNP sent 3 notices ordering Mendoza to return the M16 assault rifle issued to him in 1994, which he used in Monday's hostage-taking incident.

Once a policeman is dismissed from the service, he should immediately surrender the firearms issued to him as well as his badge.

If he fails to do so after 3 notices, the PNP will file a case against him and will issue a warrant of arrest to recover the firearm and badge.

The policeman will also not be able to receive clearance. If he is retiring, he will not get his retirement benefits.

Cruz said Mendoza ignored the notices and insisted that he should not return the firearm because he filed a motion for reconsideration on his dismissal order.

After 31 years in the police service, Mendoza was dismissed following a recommendation from the Office of the Ombudsman, which found him guilty of extortion in 2008.

Cruz said that the PNP was supposed to file a case against Mendoza for failing to return his firearm until he hijacked a tourist bus filled with Hong Kong tourists. The ex-policeman demanded to be reinstated.

Aside from the assault rifle, the dismissed policeman was also armed with a .45 pistol, which, police said, was a loose firearm.

The police spokesman said crime scene investigators recovered 50 bullet shells from an M16 rifle. The PNP's Crime Laboratory has yet to determine if the bullet shells came from Mendoza's issued firearm.

Cruz has also said that there is "a certain degree of certainty" that the bullets that killed the 8 Hong Kong tourists came from Mendoza's firearms.

Police investigators have also conducted ballistics tests on the firearms used by policemen in the bus assault.

There are suspicions that some of the Hong Kong tourists could have been hit by stray bullets during the exchange of shots between Mendoza and the assault team.

Police investigators have brought the Hong Thai tourist bus to Camp Bagong Diwa in Taguig City for further forensic tests.