A CHARACTER portrait of letter bomb victim Michael Coyne was offered last night by Mr Norman Smith, a past president of the Association of British Investigators.

''I have known Mike for some time. He runs an established agency. He has a CID background and I would have thought that whatever he was involved in, he would have dealt with it in a fairly down-to-earth, objective fashion. It may well be that this is the one individual who has decided to seek some kind of twisted vengeance. I don't think there is anything that Mike Coyne would have done that was untoward.''

Mr Smith has been subjected to physical attacks in his own work. ''But I think you can say that this attack on Mike Coyne and his wife is, in my experience, unique. That is not to say that there are not potentially dangerous aspects about the business, particularly on undercover work and sometimes in connection with what may appear to be simple work such as serving legal processes, because one is dealing quite often with vulnerable people and naturally their reaction is going to be perhaps hostile.

''But I think you could say that an investigator who acts with absolutely integrity, confidence, and sensitivity is not going to involve himself in punch-ups every five minutes. For 99% of the time the potential for danger is nullified.''