TAIPEI (Taiwan News) -- Despite public proclamations by his celebrity parents that he was "just kidding," the Taiwanese exchange student An Tso "Edward" Sun (孫安佐) arrested last week for allegedly threatening to "shoot up" a private school in Pennsylvania has been found to have acquired 1,600 rounds of ammunition and to have assembled a 9 mm handgun.

Upper Darby Police Superintendent Michael Chitwood on Monday revealed more evidence that they have discovered in a black bag which contained ammunition for an AR-15, AK-47 and an untraceable handgun Sun had assembled. Based on the evidence gathered so far, Chitwood said "we certainly feel he was going to shoot down the school."

According to police, the bullets found to have been acquired by Sun included 225 rounds of 12-gauge shotgun ammo, 663 rounds of 9 mm ammo, 295 round of AR-15 ammo, and 425 rounds of AK-47 ammo, as well as other types of ammunition. The 9 mm handgun was assembled by Sun from untraceable parts he had purchased online.

Chitwood said that much of the new evidence was found in a black bag that the host parent had found in Sun's room and hid before police arrived for their initial search, but he did not reveal where police were able to find the bag. “Subsequently we were able to locate the ammo in a different spot and we got a statement from the host family/parent, and we’re still investigating that,”said Chitwood.

On March 26, the 18-year-old An Tso Sun allegedly warned a 17-year-old classmate not to attend class at Monsignor Bonner Archbishop Prendergast Catholic High School in Upper Darby, Pennsylvania on May 1, as he said he "was going to shoot up the school" that day, according to police. The classmate then notified a school social worker, school authorities notified the police and An Tso Sun was arrested a 9:38 a.m. the next morning after allowing a detective to question him.

On March 27, a search of his living quarters turned up a garrote, a crossbow, a ballistic vest and ammunition, but no gun. Police said he had been searching online for information on how to buy an AK-47 assault rifle or an AR-15 semiautomatic rifle.

Sun's mother, Di Ying (狄鶯), who is a famous TV and Taiwanese Opera actress, told local news channel SET News that the boy had just made those threats as a joke to his friends and the prop gun that the US police had found in her son's room were in fact bought in Taiwan and taken to US by Sun to use for a Halloween outfit. She also emphasized that the threat made by her son was either a joke or just a language misunderstanding and has confirmed with the news channel that she has hired a lawyer for her son in the United States.

In a statement released to the media on the afternoon of March 30, the young man’s father Taiwanese actor Sun Peng (孫鵬) apologized on behalf of him and his wife Taiwanese opera singer Di Ying (狄鶯), and said the couple would accompany their son and only child to face the legal process in the United States. Sun said that their son's troubles have caused a lot of concern from all walks of life and expended a lot of social resources to report on the incident, "We feel very sorry."

On March 31, both celebrity parents arrived in the U.S. to assist their son with the legal process.

Sun has been expelled from the school and remains in jail in lieu of US$100,000 bail on charges of making terroristic threats. A preliminary hearing on the case will be held on April 11.