London - Joanna Dennehy admitted killing Kevin Lee, 48, Lukasz Slaboszewski, 31, and John Chapman, 56, who were found with multiple stab wounds between March and April this year.
Mr Lee's body was discovered dumped in a ditch in Newborough, Cambridgeshire, on March 30, and her other two victims were found a short distance away at Thorney Dyke.
Dennehy, 30, also admitted the attempted murders of two other men, John Rogers and Robin Bereza.
The pleas appeared to take her defence barrister Nigel Lickley QC by surprise.
Mr Lickley said: "The course is not one I had anticipated. We ask for more time given what has just occurred."
Dennehy, who sat in the dock of the court, said she did not want to talk to anyone and added: "I have pleaded guilty and that's it."
Her partner, 7ft 3inches tall Gary Stretch, 47, denied the two attempted murders and helping Dennehy to dump the bodies.
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