Semret died when she was stabbed from behind on Oct. 23, 2012, while walking home from work at around 7 a.m.
Semret, 55, had just finished a night shift as a supervisor of a cleaning crew at the Delta Chelsea Hotel. Security video from the area released by Toronto police shows her walking down a laneway connecting Bleecker Street to Ontario Street prior to the attack.
On Monday Det. Sgt. Gary Giroux held a news conference to update reporters about the case. He said a DNA analysis of blood found at the scene and under Semret's right fingernail is a match, suggesting Semret scratched her attacker.
The attacker's blood was also found on a bag and on an umbrella that Semret was carrying.
Police say the knife used in the attack was large (at least 20 cm long) and is likely a kitchen-style knife.
Giroux said some of the blood spilled at the scene belongs to the attacker, suggesting he may have stabbed himself during the attack, which happened on a dark, rainy morning. Giroux said the wound would likely be to the attacker's arm or hand.
"That wound may or may not have been medically treated," said Giroux.
Police also announced a $50,000 reward for any information that leads to a conviction in the case.
Anyone with information is asked to contact police at 416.808.7400. Tips can also be sent anonymously to Crime Stoppers at 416-222-TIPS (8477)