Four youths appeared in a New Zealand court Wednesday to face charges relating to a Japanese student whose body was found in a river on Sept. 25.

The four youths -- three aged 17 and the fourth 16 -- have all been charged in the Christchurch District Court with assault with intent to rob and dishonestly using a document, police said in a statement.

One has also been charged with stealing the belongings of Yasuaki Shishikura, 23, who had been studying in Christchurch since April and had been due to return home to Japan this month.

Shishikura's body was found in the Heathcote River with a head injury and a minor injury to his ribs.

Police said he was alive when he went in the river. While they recovered his diary, backpack and wristwatch, his bank card and credit cards are missing.