PC Sean Fahey, 53, was given the warning on Tuesday (September 5) following a one-day hearing, where he was accused of breaching the standards of professional behaviour.
The hearing heard that, between September 1 and December 20 last year, PC Fahey allegedly neglected to perform his duty by failing to appropriately manage a sex offender.
Earlier this year, on July 3, he was given a 16-month suspended sentence after admitting to signing the sex offenders' register to show a pervert who disappeared was still attending appointments.
The officer, who was part of the Jigsaw Team in Ealing , was then responsible for keeping an eye on around 50 sex offenders in the area.
Southwark Crown Court heard that, in September 2016, the officer was “struggling” to keep up with the workload when one man, known as “X”, vanished.
He had no idea the man had returned to Afghanistan and was not prowling streets in west London.
Rather than report the breach, the officer completed the register to show the man, who was convicted of sexual assault and ordered to sign on for 10 years, was still showing up.
PC Fahey was convicted of wilfully neglecting to perform his duty and wilfully misconducting himself whilst the holder of a public office.
He received the suspended sentence on July 3, was ordered to carry out 150 hours unpaid work and was also made to pay £450 of costs.
The Special Case Hearing, held on Tuesday (September 5), also heard that on three separate occasions between April 4 and April 24, he wrongfully accessed the electronic case file for his own criminal investigation for misconduct in a public office.
'A man ashamed of his actions'
The chair found the allegations proven as "gross misconduct".
Assistant commissioner Patricia Gallan, who chaired the hearing, said: “This officer has admitted his guilt in court, he has been punished in the court, and he has shown his remorse at this hearing.
“His demeanour is of a man ashamed of his actions, who bitterly regrets what he did.
“A final written warning is a fair sanction given the mitigation and evidence I have heard.”
The officer has since expressed his intention to resign.
Keep up to date with the latest news in west London via the free getwestlondon app.
You can set up your app to see all the latest news and events from your area, plus receive push notifications for breaking news.