PC Trevor Godfrey was found by an independent panel to have committed misconduct at a hearing which began yesterday, confirmed the spokesman for the Independent Office for Police Conduct (IOPC).
PC Godfrey retired from the force in December 2017 so will face no further action, the spokesman said.
In May 2019 PC Mills, who also left the force prior to disciplinary proceedings being held, was also found to have committed gross misconduct and was placed on the police barred list, confirmed the spokesman.
Shana Grice was stalked by her ex-boyfriend Michael Lane before he murdered her at her Portslade home in 2017.
IOPC Regional Director Sarah Green said: “The murder of Shana devastated her family and friends.
“The circumstances surrounding her murder have understandably led to concerns being raised about how Sussex Police handle such situations.
“I would like to offer reassurance that we made a number of quick time learning recommendations that the force has accepted and we will make further statutory recommendations to improve how police handle reports of domestic abuse.
“PC Godfrey has been found to have committed misconduct for failing in his duties and responsibilities towards Shana, and for acting unfairly towards her by not further exploring the context of her relationship with Mr Lane, and by effectively reaching a conclusion without making proper enquiry.
“Those close to Shana have testified that his actions affected her confidence in the police and may have prevented her from reporting Lane’s continued harassment.”
Learning recommendations made to Sussex Police
The IOPC launched its investigation following the murder of Ms Grice in Portslade in August 2016.
The investigation examined the interactions between both Ms Grice and Lane with Sussex Police in the months leading up to her death.
In total, 14 individuals working for Sussex Police were served notice that they were under investigation, the spokesman said.
The spokesman said: “We made six quick-time learning recommendations to Sussex regarding how it handles allegations of stalking in April 2017 and are preparing to formalise 16 learning recommendations formed from our investigation, as well as two national learning recommendations.
“Our recommendations cover issues such as implementing best practice in handling allegations of harassment and stalking, improvements in training and limiting the use of fixed penalty notices on victims of domestic abuse.”
Alongside the findings against PCs Godfrey and Mills, a third officer was given a written warning after being found to have committed misconduct and three other officers received management action, the spokesman said.
The investigation concluded there was no case to answer for the other six individuals with Sussex Police, confirmed the spokesman.
Ms Green said: “During our investigation and subsequently, Sussex Police have responded positively to our suggested learning recommendations about how to improve their handling of allegations of stalking and domestic abuse.
“These learning recommendations are now due to be formally submitted and we will continue to work with Sussex and also the College of Policing regarding their implementation.”
A timeline of the incident
February 2016 – Ms Grice approached police with concerns she was being stalked by Michael Lane
March 2016 – Sussex Police were contacted regarding an alleged assault on Miss Grice by Mr Lane.
During the police investigation it was revealed Miss Grice had been in a relationship with Mr Lane and she was subsequently fined for wasting police time.
July 2016 – Ms Grice reported Mr Lane to police for stealing her house key, entering her home and entering her bedroom as she slept.
Mr Lane was arrested and given a police caution for theft of the key.
July 2016 - The next day Miss Grice called the police again after receiving a number of missed calls from a withheld number.
It was later established by Sussex Police these calls came from Mr Lane’s home but Miss Grice was not informed.
July 2016 - Miss Grice complained to Sussex Police Mr Lane had followed her to work.
She was told an officer would deal with this, and told the same information when she called later for an update.
August 2016 - Mr Lane entered her home and murdered her