The parents of a woman who was accused of wasting police time five months before she was killed by her ex-boyfriend have denounced disciplinary proceedings against the police officer involved as a sham after he was found not to have committed gross misconduct.

A panel sitting in Lewes, East Sussex found Trevor Godfrey failed to adequately investigate Shana Grice’s allegations of harassment and stalking and failed to treat her as a victim – behaviour that amounted to a breach of police rules. But it said his actions amounted to the lesser disciplinary offence of misconduct for which Godfrey, now retired, would not have been sacked, were he still working.

The panel chair, Victoria Goodfellow, said: “While clearly serious matters, they are not enough to mean gross misconduct. We do not attribute any blame on Shana.”

Sharon Grice and Richard Green said: “The misconduct charge is a joke and the hearing a sham.”

They added: “We can barely believe what we have witnessed these past two days. The panel allowed a wholesale character assassination of our daughter, who is obviously not here to defend herself. Godfrey’s testimony only proved his discriminatory attitude, even accusing Shana of coercing Lane. We can barely believe what we have heard.

“To add insult to injury, we have been subjected to aggressive and bullying tactics from Godfrey’s representatives, yet we were the ones accused of trying to intimidate him.”

The couple asked: “What message does this give to other officers? Even more importantly, what message does it send to victims? We are disgusted and feel thoroughly let down by the process. There is no justice.”

Grice, 19, was murdered by Michael Lane at her home in Brighton on 25 August 2016. She had reported Lane to police five times in six months and had been fined for wasting officers’ time after she initially failed to disclose their relationship. The harassment case was closed before her pleas for help were properly investigated.

The hearing was told that Godfrey was tasked with investigating an allegation of common assault on 25 March 2016 after Grice claimed Lane had chased and made physical contact with her.

During an interview, Grice made a number of other allegations against Lane, including that he had sent her flowers unsolicited and made numerous attempts to contact her. Lane was arrested and told Godfrey the pair were in a relationship, and provided details of mobile phone messages to back up his story.

Grice admitted she was having an affair with Lane, and in an 84-second phone call Godfrey told Grice she would be fined for wasting police time over the harassment allegations – a decision ratified by police bosses.

Godfrey stood by the decision when giving evidence to the misconduct panel. He said: “She [Grice] lied to police three times. It was only right I advised her she cannot keep lying in police statements and getting people arrested for it.”

James Berry, presenting the case against Godfrey, accused him of applying an inaccurate stereotype that a woman could not be at risk from a man with whom she was in a relationship.

Godfrey replied: “I don’t have those views … There was no history of violence between them, there was no evidence of violence, or risk, at that time.”

He said there was no sign of Grice being harassed. She had admitted that on one occasion Lane had waited outside her house late at night because she had arranged the meeting behind her boyfriend’s back.

Godfrey said: “She would be signing her texts [to Lane] with five kisses. This is not harassment. It was a smokescreen to disguise her affair.”

He said there was therefore no reason to supply Grice with safety advice regarding her relationship with Lane. “She was in an active relationship with him for six months. I can honestly say, hand on heart, there was nothing there to suggest she was in any form of danger whatsoever.”

Summing up the case against Godfrey, Berry said there was a “serious failing” in Godfrey not filling out a risk assessment form.

“Mr Godfrey simply lost his impartiality and Lane became the victim and Shana became the wrong-doer … Mr Godfrey’s handling of this case did not represent the impartiality expected of a police officer,” he said.

Mark Aldred, representing Godfrey, said: “It is easy to lapse into ‘the officer should have done, ought to have done, could have done it differently’. This is about gross misconduct, so there must be evidence or a positive duty to do something in a particular way. Decision-makers don’t make a decision in a vacuum.”

Lane, 27, was jailed for life with a minimum term of 25 years after he was convicted of Grice’s murder.

In April, another officer was found to have committed gross misconduct when investigating Grice’s report that Lane had broken into her home with a stolen key. PC Mills would have been sacked, had he not already resigned.