Yeh Kun-fu, head of the police bureau in the central Taiwan city, said the 40-year-old suspect, identified as Wang Chiang-sheng, has admitted that he alone was involved in the extortion plot.

Wang addressed a threatening letter to Tunghai University President Haydn H.D. Chen on Thursday, demanding that NT$5 million in cash and 50 taels of gold be placed at designated locations, or he would poison the university's water supply.

According to police, Wang had made a series of phone calls the previous two days in which he gave instructions on where the money and gold should be placed.

In one of the phone calls, he asked Tunghai University administrators to relay a demand to seven other universities and colleges in Taichung County that they must each remit NT$80,000 to a designated bank account, or their water supplies would also be poisoned.

Police traced several of the calls to a public phone. They used footage from nearby roadside close-circuit television cameras to find the registration number of the motorcycle used by the person making the phone calls.

After establishing that the suspect was a man living in Daya Township in Taichung County, police zeroed in on him Saturday night. At his home, the officers found information gathered from the Internet about the universities in Taichung County.

At first Wang denied that he was behind the extortion plot, but after police laid the evidence in front of his eyes, he admitted that he planned the scheme because he needed the money badly to pay off his debts.

Police officers who examined the water supplies of Tunghai University removed a bag of rat poison hanging in a water tank. Wang admitted that he placed the poison there on the day when he wrote the threatening letter to Tunghai's president.

Wang will likely be handed over to the Taichung Public Prosecutors Office for further investigation on suspicion of intimidation and extortion.