From the fact that the culprit went out of his way to phone Kudo-kun, he either wanted to challenge the famous high school detective, or he's someone with a personal grudge against him.
不过从犯人特地打电话给工藤这点来看 他或许冲着高中生名侦探工藤新一的名气来挑战 不然就是跟他有私人恩怨的人