Barking_Mad said:
So if police can amend entries in the book and it happens on a fairly regular basis then how would someone investigating a case of possible police malpractice know whether they had been amended in genuine error or in an attempt to cover a situation up?
That is a VERY important question whenever you are considering physical trace evidence. The first issue is to establish what (if anything) you've found (fingerprint, DNA, indented writing ...). The second is to establish
what it means. This is sometimes known as it's [/i]evidential value[/i]. Sadly many people (and I include many senior investigators, CPS lawyers, counsel, judges and every other type of participant in the criminal justice process here) dn't move beyond stage 1 or, if they do, they take a less than thorough approach to stage 2.
If (and I don't know for sure, but I can think of no obvious other scientific test) if was ESDA then what will be found will be indented writing (i.e. the hollows made in a piece of paper when another piece of paper above it is written on). If you write a letter in one go, on a pad where the top page is held steady (e.g. by a gummed strip) then the exact replica of the words you write should be visible on the sheet below (and, usually several below that at normal writing pressure) when it is ESDA'd.
If you leave turn the page (but don't detach it) and then flip it back and add another word, it should be in pretty much the same place in the indented version as in the top version - certainly not massively different.
If, however, the pages are loose leaf, and you pick one out and add a word later, you may, or may not, have the same pieces of paper underneath. And even if you do, you are unlikely to align them in exactly the same position. So the additional word is either missing or in the wrong place on the indented impression.
Sometimes (especially if a roller-ball type pen is used, which leaves a layer of ink on the paper surface) you can microscopically see if an indentation came before or after the layer of ink, so you will be able to tell if an indentation came before or after writing on the lower page.
Because there are so many possibilities, some of the innocent, some of them procedural errors and some of them out and out criminal, you need to establish what the circumstances of the writing of the log were.
The first question I would ask would be "How (exactly) was the log compiled?" By who? Where? Contemporaneously? On what (I would expect it to be a bound surveillance log with serially numbered pages in this case)?
I would then ask about whether anything could have been added or changed later? Was there a debrief? Did all the individual members check the entries made by any logkeeper about things they had seen? If they found an error, how did they change it?
And if this did not give me my answer, I would specifically put whatever it is I had found scientifically. (e.g. "ESDA analysis shows the word "Not" was not written at the same time as the rest of the entry timed at 9.30am. You have said it was all written contemporaneously, filling one page before you turned over, and that no-one has since made any corrections. Can you explain how this may have happened?"
Despite the implication in the original leak, there is NO scientific technique which tells you that an alteration has been made dishonestly. There are just some which MAY tell you that an alteration has been made.