Three doctors who signed cremation forms for Harold Shipman were cleared of professional misconduct on Thursday.
Harold Shipman murdered about 250 patients with morphine
They had been accused of failing to notice "extraordinary coincidences" between timings of killer Shipman's home visits and patient deaths.
Doctors Jeremy Dirckze, Stephen Farrar and Alistair MacGillivray all worked in surgeries close to the GP's practices in Hyde, Greater Manchester.
The General Medical Council has yet to decide on the case of a fourth doctor.
Susan Booth has also denied the charge of serious professional misconduct at the hearing before the General Medical Council's (GMC) Fitness to Practise Panel in Manchester.
It had been claimed the four doctors countersigned cremation forms for mass murderer Shipman without adequate checks.
Clearing the three doctors, panel chairman, Dr Linda Buchanan, said: "The cases considered by the panel during this hearing have concerned one doctor, Dr Shipman.
"He was highly regarded, thought to be a skilled and caring family doctor and was widely respected among his patients and professional colleagues.
"It has subsequently been established that, while the overwhelming majority of doctors are honest and truthful, he was an accomplished liar who set out to deceive his patients and colleagues alike, even going so far as to create false record in his patient notes."
Jailed for life
Dr Buchanan added that the case against the three doctors was "insufficient to amount to serious professional misconduct".
Two further doctors, Peter Bennett and Rajesh Patel, were also cleared of the same charges in December last year. Doctors Dirckze, Farrar, MacGillivray and Booth worked at the Clarendon House and Brooke practices, close to Shipman's former surgeries, Donneybrook and Market Street.
Shipman is thought to have murdered about 250 people in a 27-year career.
He was jailed for life in January 2000 after being convicted of 15 counts of murder at Preston Crown Court, and was found hanged in his Wakefield prison cell four years later.
Since Shipman's arrest and the subsequent inquiry, the system of signing cremation forms has been under review.
There was mixed reaction to the GMC's decision among relatives of Shipman's victims.
Andrea Robinson, 38, lost her mother Eileen Robinson to the serial killer when she was only 54 in December 1993.
She said she was disappointed with the outcome of the hearing and added: "Somebody must have noticed something was wrong as so many more of Shipman's patients were dying."
The daughter of Bessie Baddeley, who was killed in November 1997 when she was 83, said she was pleased with the GMC's decision.
Kathleen Wood, 63, from Hyde, said: "No-one in the Hyde area suspected him of anything, so I honestly don't believe that these doctors should have been blamed."