The parents of Karin Grech, who was killed by a letter bomb more than three decades ago, are insisting that police continue investigating the murder of their 15-year-old daughter.

"Since Karin was murdered in our very home, on December 28, 1977, we've never enjoyed the Christmas festivities. The trauma is there all the time. You learn to live with it but it's always there," her father, Professor Edwin Grech, says softly.

As he sits on a bench at the Upper Barrakka Gardens in Valletta, Prof. Grech gazes into the distance and, as his tone gets harsher, he adds: "The worst thing is the lack of justice. To leave the case unattended and unsolved was cruel to us... as cruel as killing Karin."

Prof. Grech and his wife Pearl, who live in Gozo, travelled to Malta for the day yesterday to visit Karin's grave and attend a memorial Mass to commemorate the 32nd anniversary of her murder.

The case was rekindled in the nation's memory last week when a parcel bomb was delivered to a Qormi home and exploded in the hands of 60-year-old Philip Cini.

His wife and eight-year-old grandson were standing close to him but escaped uninjured. However, Mr Cini lost his left hand and suffered serious injuries to the left side of his torso. He remains in critical condition.

When Prof. Grech, now 80, heard about the Qormi case he could not believe such things still happened. "To do something like this is unpardonable," Prof. Grech, a former Labour minister, said.

He points out that the main difference between the two cases is that the bomb that killed his daughter passed through the postal system, while the Qormi explosive was dropped off on the doorstep.

Apart from that, in last week's case the motive has not yet been established. "In my case there was only one motive - medico-political - because of the doctor's strike. I cannot prove it myself but ... I believe it can be proven," Prof. Grech says.

Karin died when she opened a letter bomb addressed to her father during the doctor's strike in 1977.

It is believed the bomb was sent to Prof. Grech, a gynaecologist, because he was considered to be a strike breaker.

A similar letter bomb was sent to general practitioner Paul Chetcuti Caruana but this never exploded.

"Our duty as doctors is to treat patients. Looking back, I would have done the same thing and kept treating patients... Why didn't they shoot me while I was out? Did they have to send the parcel home? They should be ashamed," he says.

His expression turns to one of disgust as he thinks of how the perpetrator had wrapped the bomb in Christmas wrapping and sent it home.

"At the time, being a doctor, I used to receive lots of mail and gifts. The day the bomb was delivered to our home in San Ġwann, the postman knocked at the door since it did not pass through the letter box... Karin and her younger brother, Kevin, passed it to one another to open it," he recalls.

Karin opened it. Inside the envelope there was a small pen-box shaped parcel. When she opened it, it exploded.

"She was a 15-year-old attending school in Britain where I used to work. We left her at the college there not to interrupt her schooling.

"She was in Malta for the Christmas holidays... They picked the worst time of year to send it," he says.

After the explosion Prof. Grech and his wife wrapped up their bleeding daughter in towels and took her to hospital. But she died soon after.

"Time does not ease the pain. I feel that if she had been taken through natural causes, it would have been a terrible thing, but it would have been acceptable. Doing something like that, and at Christmas, is unacceptable," he adds.

Since then Prof. Grech has been waiting for the police to bring his daughter's murderer to justice.

In January 2008 his family initiated a compensation case in the First Hall of the Civil Court in its constitutional jurisdiction.

The family is arguing they were discriminated against for not being paid compensation from the government like other families who fell victim to crime. The case is still pending.

"If there is anyone who merited compensation for criminality it's us... This is a point of principle. The last thing the Grech family wants is compensation.

"Who can compensate us for Karin? I'm not doing this for money... I would prefer if they solved the case. I will continue hammering on this until my eyes don't open again," he insists.