Waseem Daker was convicted in Marietta, Ga., for the 1995 murder of Karmen Smith and the stabbing of her 5-year-old son.

Waseem Daker, the man convicted last week of murdering a Georgia woman and repeatedly stabbing her 5-year-old son was sentenced today to life in prison, plus 47 years.

Karmen Smith was killed in her home in 1995. Her son was stabbed 18 times but survived.

Daker, who represented himself during his trial, argued again today that he was not guilty of the crimes.

"I did not kill Karmen Smith. I did not stab Nick Smith," he said, "I hope that one day the truth comes out, because this is not it."

But the judge in the case called Daker "a master manipulator."

"I hope you never leave prison because that will be just," Cobb County Superior Court Judge Mary Staley said.

Nick Smith, the son, now in his 20s, testified against Daker - and was cross-examined by him - during the trial.

""From what I could tell it was a man, but it was really dark and I just assumed that it was someone that I knew. … The person in the room grabbed me and started stabbing me a bunch and I tried to yell and he covered my mouth and then he kept stabbing me," a teary Smith told the courtroom.

Before he was tried for Karmen Smith's murder, Daker spent 10 years in prison for stalking Smith's roommate, Loretta Spencer Blatz.

Blatz also testified against Daker at the trial.

Watch the full story on "20/20? Friday at 10 p.m. ET.

ABC News' Adam Sechrist contributed to this report.