MARIETTA — On what would have been his mother’s 47th birthday, a tearful Nickolas Smith recounted for jurors the day 17 years ago when he was stabbed 18 times in his east Cobb home by a man who was wearing a black mask.

Smith is now 22 and a recent graduate of the University of Georgia. He spent about 30 minutes testifying Tuesday morning, even raising his shirt to show scars that remain on his torso from the attack.

His mother, Karmen Smith, was found stangled on Oct. 23, 1995. Tuesday would have been her birthday.

Smith said that when he came home from kindergarten at Timber Ridge Elementary that day, his mother’s car was in the driveway, so he thought she was home in their basement apartment on Old Hunter’s Trace, in east Cobb. He and his mother typically accessed their apartment through a sliding-glass door on the back of the house, he said.

Smith said he first called out to his mother, but got no answer and went to the upstairs of the house. Later, he went back to the apartment and could see there was someone in the back of the apartment. Assuming it was someone he knew, he kept walking into the apartment.

“The person in the room grabbed me and started stabbing me,” Smith said, his voice at times a whisper. “He threw me down. I started screaming and he covered my mouth and kept stabbing me. I got up and fainted.”

The attacker was a man wearing a dark mask and dark gloves, Smith said, adding that he didn’t realize he was being stabbed.

“It felt like I was being punched a lot,” he said.

Relatives of Smith’s in the courtroom were visibly upset during his testimony, as was at least one juror.

Prosecutor Jesse Evans asked Nickolas Smith if he knew who stabbed him.

“No one I know would ever do that to me,” Smith said.

The attacker then ran out the back of house, he said.

“I was lying on ground and could see through the window, a shadow running up back toward driveway,” he said.

On cross examination, defendant Waseem Daker, representing himself, asked Smith if he recalled statements he made to detectives in 1995, that his attacker had blue eyes, but Smith said he did not.

Later, with a former Cobb police detective on the stand, Daker played an audio tape of detectives interviewing Nickolas Smith in his hospital room the day after the attack in which he said the attacker’s eyes were blue.

Earlier on Tuesday, jurors heard testimony from Christina Valenti, who was 10 at the time and lived in the upper part of the same house with her mother, Loretta Spencer Blatz.

The trial is expected to last three weeks. Prosecutors say it was not until 2009 that nuclear DNA tests on hairs left at the crime scene linked Daker to the murder of Karmen Smith and the stabbing of Nickolas Smith.

Daker is apparently only the third murder defendant in Cobb County in memory to try representing himself. John Wilkerson did in his 2006 trial, but was convicted of killing his roommate. Jack Potts tried it in 1990, but was convicted and sentenced to die for killing a good Samaritan.

Daker could get life in prison if he is convicted of murder. He is not eligible for the death penalty because he was 17 at the time of the crime.

The defense witness list includes dozens people, many of them police. Marietta Police Chief Dan Flynn is among the defense’s witnesses, though it’s not clear why.

“I am on the list although the murder occurred 12 years before I even came to Marietta,” Flynn said. “I have no first-hand knowledge of anything about the case.”