A man accused of the murder of five women in Suffolk became "sloppy" in his "campaign of murder", jurors heard.
The five women were found dead around Ipswich in December 2006
Prosecutors told Ipswich Crown Court how red fibres on some of the women pointed to how Steve Wright disposed of their bodies in a blanket.
Peter Wright, prosecuting, said Mr Wright's sloppiness had meant he left vital clues leading police to charge him with the five murders.
Mr Wright denies killing the women, who were all discovered around Ipswich.
Annette Nicholls, Paula Clennell, Tania Nicol, Gemma Adams and Anneli Alderton, who all worked as prostitutes, were found dead during a 10-day period in December 2006.
In cross-examination, the prosecutor asked Mr Wright about the red fibres: "They came from the blanket in which you carried some of the bodies. That's where they came from, didn't they?"
Mr Wright denied this.
The court heard how Mr Wright's Ford Mondeo car, which he previously said he cleaned weekly and "vigorously", was found with a Mars bar wrapper and cigarette butts in at the time of his arrest.
Fibres and DNA linked to the women's bodies were also discovered.
The prosecutor said: "Is it that the position you had reached was this, Mr Wright? So successful had you been at picking up these women and killing them that you were getting sloppy?"
Mr Wright said: "No way. I had nothing to do with their deaths."
The counsel continued: "You engaged in a campaign of murder for a little over six weeks. That's the truth, isn't it? You selected women with which to have sex with and to kill."
"No, I did not," Mr Wright replied.
Mr Wright told jurors he suffered from insomnia and had gone for a drive when they were shown a photograph of his car leaving Ipswich shortly after Miss Alderton and Miss Nicol were last seen.
The defendant was earlier asked: "How did [Miss Nicholls'] blood get on the outside of the back of the right sleeve of your jacket?"
Mr Wright replied: "I couldn't say."
The counsel then said: "How did [Miss Clennell's] blood get on the back of your left shoulder?
"I have no idea," Mr Wright responded.
Finishing giving evidence, Mr Wright denied that he had tried to "tailor" his explanations to fit prosecution evidence.
The trial adjourned.