Testifying in the case against Frank S., the man who attacked her on October 17th, Reker described how he seemed friendly at first when he approached her on the campaign trail last year.
She was on a meet and greet at the Cologne Braunsfeld market on the day before the election, when S. approached her and asked for a rose.
The 59-year-old took a few steps towards him before seeing the weapon.
“At that point he already had the knife pulled,” she told the court.
Within a fraction of a second, he had stabbed her in the neck with a hunting knife.
The blow completely severed her airpipe and S. had plunged the weapon into her so deep that he split one of her neck vertebrae.
“I fell to the floor immediately and noticed that I was bleeding from the mouth and nose.”
Reker, who at the time was running as an independent candidate for the mayoral post, remembered first aid training she had received early in her career.
“I put myself in a stable position on my side and put a finger in the wound to squeeze it.”
She then concentrated on not moving so as not to make the damage any worse.
"My greatest fear was that I would be paralyzed," Reker said in the witness box. "I had the feeling that my throat had been slit, that is basically a method of execution."
Throughout the ordeal she remained conscious, she said, all the way up to arriving at hospital, where she was put into an induced coma.
According to his own testimony, S. deliberately sought Reker out on the day before the election to "send a signal" against what he believed to be Germany’s misguided refugee policy and the "organized destruction of the country".
S. was once active in the far-right political scene in the neighbouring city of Bonn.
The defendant denied, though, that he intended to kill Reker, who he described during his testimony last week as "a completely deluded, far-left, fancy pants ideologue".
Reker had been head of the city’s social welfare department before the elections and was responsible for planning housing for refugees.
She first learned of her success in the election four days later, when she woke from an induced coma.
Doctors told her she had been extremely lucky that a major artery or her spinal chord had not been affected.
The mayor told the court that she was not afraid of large crowds of people as a result of the attack, but that she had recurring nightmares about being executed.
"But they always end before something happens to me. I only dream until the point when the hood is pulled over my head."
Reker rejected an offer from the defence that S. could give her "a few words of apology".
"I don’t think it is yet the right time for it," she replied, chokingly.