The question would have probably remained unanswered except for a re mark made to John's father, David, by the family doctor after his funeral last June. As shocked as everyone else, she had gone through his medical records to see if there had been any previous hint of depression. There was none. However, she saw that John had been prescribed anti-acne tablets by a dermatologist to whom she had referred him. When she looked up the drug, Roaccutane, she saw that listed among its side-effects were depression and mood changes.

In the following weeks, David started to gather information on the drug. It began with simply looking at the product information leaflet but has since mushroomed into an international search for information.

He has been in contact with health agencies all over the world, employed a researcher and said he has had an ongoing battle with Roche, which manufactures the drug, to get information on its side-effects and other cases of suicide among people prescribed it.

"We were utterly devastated when John committed suicide. It was difficult for us to even believe he had ever contemplated it. He was tall and attractive and very well liked. Even when we went to the hospital morgue, the nurse there said he was so good-looking she just could not believe it. He had everything to live for. The family is still in shock. At night now we keep a light on in the landing. It's been like that since John died."

John, a second-year electronics engineering student at UCD, had no history of depression, according to his family, and had showed no signs of mood swings before taking Roaccutane. He loved music and his ambition was to open a sound studio in Temple Bar. He played drums and guitar and was a member of two bands.

His family say his acne was not severe, but he was conscious of it. A neighbour was on Roaccutane, and John asked the doctor about getting a prescription. She referred him to a dermatologist and he was first prescribed the drug in mid-February.

Speaking now about his death, John's parents say he had become distant in the months preceding his death. He stayed in his room for longer periods, stayed out later than usual and all night on Saturdays. His friends also noticed the change.

"It was completely different from his normal routine, but we thought it might have been pressure over his exams. Of course, you keep thinking about what you should have done or what you should have noticed. We knew he was on tablets for acne but we were never told that depression was a side effect and we don't think John knew about it either."

He committed suicide during a weekend when his parents were away at a family reunion. When they returned they found a note on his bed. They discovered shortly afterwards that he had cycled to the Dublin mountains and hanged himself. Located close to the road, his body was spotted by a passing motorist a few hours later. His locked bicycle was found nearby.

There were five Roaccutane capsules left unused at the time of his death. Two empty wrappings were found in his trousers when his body was discovered.

After John's GP mentioned the side-effects of the drug, his father wrote to Roche in July. "I received no response, wrote again in August, again in September and eventually they responded."

The letter from Roche in the UK stated that the company was prohibited by industry rules from communicating directly with members of the public about medical matters. It could communicate with the medical profession and suggested that he speak to John's dermatologist or his GP.

"I wrote asking for a copy of the industry rules. John's dermatologist informed me that Roche had provided details of six cases where depression, all male, had a fatal outcome. I wanted more information but the doctor said that Roche had insisted that a copy would not be given to me."

His investigations into the rules covering the pharmaceutical industry found no prohibition on companies dealing directly with the public on such a matter. "I had hoped that they would be open and frank in responding to my very genuine basic inquiries but they only created obstacles," said Mr Keane.

In further correspondence from the company, it said it read the industry rules differently. Mr Keane said the company stated originally that there were only six cases where depression had had a fatal outcome, then in subsequent correspondence a further three cases of "death reported where depression was either not confirmed or the outcome of depression was reported unknown". This, he said, then increased to 26 cases.

"I don't feel that I have got the true picture. I truly believe there is a problem with this drug. I want there to be an international investigation into the cases of suicide and depression."