Two-year-old Alistair Grimason was hit by a bullet as he slept in his pram after a gunfight broke out in a cafe in the Aegean seaside town of Foca in 2003.
Daimi Akyuz, 46, was jailed for life in 2004 at a court in Izmir for killing Alistair and another man during the shootout.
He was released early and six days later on Saturday, according to reports in the Turkish media, was gunned down at his own wedding in Izmir.
The toddler’s dad David Grimason, from East Kilbride, South Lanarkshire, told Press Association Scotland: “He was sentenced to 58 years with a maximum of 36, so I really expected he was going to spend a long time in jail.
“I don’t take any joy in what has happened. I would rather that he was in prison and being punished for what he did.
“I was told that he was at his wedding and stepped outside for a cigarette and someone came along and shot him.
“It’s a big story over in Turkey because the man that killed Alistair has been killed in the same manner I suppose.”
Mr Grimason has since split up from Alistair’s Turkish-born mother Ozlem, who has moved back to Izmir.
He added: “Ozlem has moved back to Turkey recently, so there was an opportunity they could have bumped in to each other. It is a horrible thought. No-one informed us that he was being let out.
“We were told at the time he would serve his full sentence. They were making an example of him. But here we are 13 and half years later and they let him out.
“We went through months of court cases. It was a tough time for us. But it’s worse for his family at the moment, I remember he had two kids.
“They’ve let him out to be killed.”
A source in Turkey said prisons are “overflowing” since the attempted coup last year and a number of inmates, who had served more than 10 years, were offered early release.
Alistair had been sleeping peacefully in his pram when he was caught in the crossfire of the gunfight. A stray bullet pierced his lung, killing him instantly.
Ozlem had been enjoying a family day-out while visiting her Turkish parents with the two-year-old.
On the evening of Monday July 7, Ozlem, Alistair and his grandmother had been at a small cafe in Foca, about an hour from Izmir.
Alistair was asleep in his pram as the two women chatted. But the peace was shattered when an argument broke out at another table.
Akyuz, who was a car salesman, pulled a gun on three others and opened fire, killing Ali Bektas, a mobile phone salesman, injuring two other men and killing the toddler.
He was found guilty in July 2004 and sentenced to 58 years, albeit Turkish law meant that he would serve a maximum of 36 years.
According to Turkish media, police are interviewing five suspects in relation to his shooting.
After the death of Alistair, his parents began campaigning for tighter gun controls.
The campaign secured more than 300,000 signatures which were presented to the Turkish parliament in December 2003.
Mr Grimason now lives in East Kilbride with his partner and three-year-old son Emil.