Dyfed-Powys PoliceLily Sullivan's body was found near Mill Pond, in Pembroke, in December 2021A man strangled a woman in frustration that she did not want to have sex with him, a judge has found.
The body of Lily Sullivan was found in Pembroke's Mill Pond in the early hours of Friday 17 December.
In June, Lewis Haines, 31, admitted murder but his defence said it was not sexually motivated.
At Swansea Crown Court, Judge Paul Thomas QC said when Lily made clear she was going home, Haines was "frustrated" and "forcibly" took her to the lake.
Although Haines, of Flemish Court, Lamphey, Pembrokeshire, will automatically be sentenced to life for murder, a special hearing was needed so the prosecution and defence could submit their cases to decide if the murder was sexually motivated.
That is key to setting a minimum term to be served in jail.
On Tuesday, the judge read out his factual findings in the case and said the two had kissed in an alley after leaving the club.
He said Lily had been out with friends when she met Haines in the Out nightclub.
They left the club separately, a few minutes apart, but started talking outside before walking to an alleyway near Mill Pond.
'Degree of intimacy'
Within hours, Haines, arrived home and told his partner: "I've strangled somebody."
Lily had injuries to her face, neck and body.
While listening to the pathologist's report earlier on Tuesday, Lily's mother left the courtroom in distress.
Delivering his findings, Judge Thomas said: "Lily Sullivan and Lewis Haines had both been drinking heavily."
He added: "Lily was two to three times over the drink-drive limit and Mr Haines was three times over it."
He said he "had no doubt some degree of intimacy was intended between them and that it occurred".
He added: "I am equally sure it didn't progress to sexual intercourse, because Lily did not want that to happen."
There was no forensic evidence of sexual assault.
When police found Lily's body in the water, she did not have her top on and it was found in vegetation close by.
Judge Thomas found it was removed "against her will" and that Haines then strangled her "and put her into the Mill Pond where she wouldn't be seen".
'He became forceful'
He rejected Haines' claim that he went into the water to save her.
"It was clear he wanted to ensure Lily died," added the judge.
"He didn't want anyone to know what had happened in that lane."
Haines had told family members that Lily had threatened to blackmail him and tell people he was "a rapist".
"My firm view is that when he became forceful, Lily did say she'd complain about what he did."
Judge Thomas said that at the time, Haines was in the middle of a legal matter and that "he had a lot to lose".
"In my view it explains why he strangled Lily and couldn't risk her surviving," he added.
Mr Haines is due to be sentenced on Friday at the same court.
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