Police don't use hollow point ammo.
Anyway why cover it up? They would have been justified in shooting Sheila if she was a threat.
The bullet they substituted was not a .22 hollow point round, it was a police round, which they swapped over with a.22 hollow point test fired control round taken from exhibit DRH/42 (29 live .22 hollow point rounds recovered from the kitchen worktop on the first morning of the investigation!) Only 27 of these 29 control rounds were accounted for during test firing performed by the ballistic expert Fletcher! When queried about these two missing control rounds in the batch of exhibit DRH/42, Fletcher told COLP that they must have been misplaced! Fletcher lied, he knew exactly what had happened to the missing two rounds of .22 hollow point rounds, he had performed unreported test firings in the anshuzt rifle prior to the date (20th September 1985) when he performed the official test firings of the other 27 control rounds! This fact is established beyond doubt by the notes recorded on various General Examination Records' pertaining to pieces of ammunition relating to the five deaths which had comparison tests performed against markings on unreported test fired rounds, enabling the said comparison tests to be performed on dates prior to the 20th September 1985! This proves there was an earlier test fire of the anshuzt rifle and control ammunition belonging to exhibit DRH/42 on or prior to 12th September 1985, because some comparison tests were carried out on 12th, 13th, 18th and 19th September 1985 (before the date when the ballistic expert had carried out the official test firing of rifle and 27 of the 29 control rounds n 20th September, 25th September, and 2nd October 1985)...
Cops and their ballistic expert didn't go to all this trouble for no purpose at all! They did it to try and cover up for the fact that a police bullet wounded Sheila during a shooting incident which occurred in the kitchen to which an Officers report had to be submitted! That report concerns the shooting of Sheila in the kitchen, claiming that she appeared to want the officer to shoot her by pulling the barrel of his gun in toward her own throat! There exists a paper trail of compelling evidence to support the fact that cops and their ballistic expert (Malcom Fletcher) tampered with at least one crime scene bullet (PV/20) by replacing it with a test fired control round which had been fired via the anshuzt rifle post the date of the shootings, so that Sheila's death could be presented as a suicide involving one gun which fired both bullets! But the same gun did not fire both bullets which wounded Sheila, the anshuzt rifle only fired one of these, that being bullet PV/19!