A case that began with the hunt for a rapist more than 30 years ago, ended with a guilty plea in a Toronto court this week.

Fifty-seven-year-old Alexander Winston Sylvester pleaded guilty Monday to two attacks – one that occurred in 1981, the other in 1993. 

It's the culmination of a long investigation that couldn't have been closed without advances in DNA technology. 

"It really feels awesome because every investigator both with Toronto and Peel police put in a lot of hours and did a lot of work to get to this point," says Const. Lilly Fitzpatrick, one of the lead investigators with Peel Regional Police.

One of the cases Sylvester pleaded guilty to was the rape of a 14-year old girl in Mississauga at gunpoint in 1981.

At the time, forensic evidence could only help determine blood type. There was no DNA technology and no offender database for police to search.

The evidence sat in storage until 2002 when Peel Regional Police Const. David Emberlin re-submitted it the Centre of Forensic Sciences.

From there, a link was made to an attack in Scarborough in 1993. In that case, a 53-year old woman was assaulted while sunbathing in her backyard. The masked man threatened to kill both her and her husband, who was at home at the time.

Fitzpatrick says the crime-scene links were the first step to finding Sylvester.

From there, Peel Regional Police analyst Hayley Giles sifted through mountains of previous case files to find the connection. The link was a 1982 rape case that Sylvester had already been convicted of.

"Hayley did an awesome job, working her magic, she went through old case files... and she came up with the name," Fitzpatrick says.

Peel Regional Police then had to contact the victim of the 1981 rape to get her help.

"I can't really describe the feeling it gave me to be able to call this young woman and say not only is your investigation being reopened but we know who did it"

But tracking down Sylvester wasn't easy. For years, he had gone back and forth between Canada the U.S., and Jamaica. 

Over the years, he racked up more than a dozen convictions for various crimes, including manslaughter.

Police tracked him down in Pennsylvania where he was serving time in a federal penitentiary.

What followed was a long and drawn out legal process involving getting DNA orders, using international treaties and multiple extradition hearings.

The process took nearly five years and Sylvester wasn't extradited until 2011.

While this week’s plea comes as a relief to officers who've spent decades on the case, Fitzpatrick says the real hero is the victim for overcoming the pain of the original incident.

The victim testified at the preliminary hearing and was prepared to testify if the case had gone to trial. 

"That's the reward in this, is to finally after all these years, be able to give this victim some closure," says Fitzpatrick. 

The Crown is seeking 15 years for the two attacks, but Sylvester is asking for a reduced sentence.

He's currently assisting police with a serious criminal investigation, the details of which are covered under a publication ban.

He will be sentenced on Wednesday.