What happens 23 years after a crime is that people can’t remember — or claim they can’t — even when it is one of the more infamous murder convictions in recent Connecticut history.

I find it hard to believe some of the central players in the Richard Lapointe murder case are having a hard time recollecting critical events from the 1987 crime.Lapointe, a mentally disabled dishwasher, was convicted in 1992 of sexually assaulting and murdering 88-year-old Bernice Martin and then setting her Manchester apartment ablaze. The conviction has been thrown into question because Lapointe’s lawyers say critical evidence was suppressed. Rockville Court Judge John Nazzaro is presiding over a one-week trial to determine whether Lapointe deserves a new trial on the murder charge.

In one of the most remarkable examples of absent-mindedness, former Manchester police investigator Michael Ludlow, now a University of Connecticut police officer, spent Monday telling the court he could not remember how he came up with his own crime scene notes that suggest a “possible burn time” of 30 to 40 minutes for the apartment fire.

The “burn time” notes did not surface at the 1992 trial, and Lapointe’s lawyers say this is one reason he deserves a new trial.

This is a potential bombshell since a fire burning this long after the murder could mean the crime was committed at a time that supports Lapointe’s alibi that he was at home. It also could raise troubling questions about the Manchester Police Department’s investigation of the crime.

Ludlow now no longer recollects how he came up with that number, telling the court, “I don’t recall where that came from.” Three years ago, he testified in a different hearing that the information came from state police investigators.

Fading memory syndrome continued Tuesday when a retired state police fire investigator took the stand. The now-retired fire investigator, Stephen Igoe, continued the litany of “I don’t recalls.” Igoe told the court — repeatedly under questioning from Lapointe lawyer Paul Casteleiro — that he never told Ludlow that the burn time could have been as long as 40 minutes. He said he doesn’t recall talking to Ludlow about this critical question.

Igoe also refused to define what a “slow” burn time could mean, saying it was anywhere from “several minutes” to “several hours.”

So where did Ludlow come up with his estimate of a possible burn time? We don’t know because nobody recalls.

•Rick Green’s column appears on Tuesday and Friday. Read his blog at courant.com/rick.