Det Supt Graham McKay made the admission while in the witness box at the fresh inquests into the tragedy for the second day.
Last week he said police officers outside the ground were ‘overwhelmed’ by the crowds and the mood got ‘nastier’ as supporters tried to get inside in time for the 3pm kick off.
Asked what his understanding of the word was, he said: “My understanding of a lemming is that it’s a small animal which at certain stages migrates and plunges to mass destruction.”
He later added he didn’t think it was an inappropriate way to describe the fans.
Mr McKay was also asked about his request to officers at a briefing the day after the tragedy not to make notes in their pocketbooks but instead to fill in a form.
He said he did this because he felt it wasn’t appropriate for ‘fragmented evidence’ to be put down in notebooks.
Under questioning from Mark George QC, acting on behalf of some of the 96 families, Mr McKay said he believed the fans were ‘at least in part’ responsible for the tragedy.
Mr McKay said even though he didn’t have evidence to support his claims, he thought some had turned up without tickets because of the ‘sheer numbers that were there’.
He added: “There seems to be a perception in some areas that Liverpool sent 5,000 Sunday school teachers across to Leppings Lane on that day. “That isn’t the case. The other side of the coin is that there’s a perception amongst some people that anyone who’s had a drink and goes to a football match is going to be unruly and behave outrageously. “That isn’t the case either. “But it was the case that a substantial number of people who arrived late at that gate had taken drink to such an extent it caused them to be ‘loud’, ‘brash’ and ‘aggressive’.”
Earlier Mr McKay was asked about his instructions to officers about their recollections of the tragedy.
He was asked by Christina Lambert counsel to the inquests what the difference was between an ‘officers report’ and a ‘statement’.
Mr McKay said: “An officer’s report would be fed into Holmes and actions would be generated from the officer’s report. “It wouldn’t itself be evidence. The evidence would come from witnesses in a statement form.”
Asked why, he said: “Because of need for impartiality - we didn’t want it to later be alleged evidence was biased.”
Mr McKay was also accused of describing the actions of police officers on the day in ‘glowing terms’ but referring to the fans as being ‘worse the wear for drink’.
He told the jury he didn’t want to denigrate the fans’ efforts, but was being accurate: “I’m not in any way trying to rubbish them I was just describing the way things were,” he said.
The inquests continue.