past guilt does not necesitate present guilt.
No, but if you are the defence lawyer and playing the good character "he/she could never possibly do such a thing" card, then you would be deceiving the jury, and a prosecutor should be able to refute that, using any information available.
I did jury service many years ago, we cleared a couple of holding a guy hostage in their house (false imprisonment), before beating and robbing him.
We'd decided 10/2 that the crime in question was too audacious to be plausible, (the victim was known to the defendants) and that the defence lawyer painted a picture of two honest hardworking down to earth people (the couple)
After the not guilty verdict was delivered, the judge asked us to remain seated while he 'dealt with another matter'
It turned out that he woman was in court that day for two reasons. One to attend the final day of her trial, the other to be sentenced for armed robbery of a newsagents, which she had done to feed her long term crack habit. and had been found guilty of in a previous trial.
We were gobsmacked. There was silence and blank expressions all round later on when 6 of the jury shared a lift back upstairs. We'd been 'had'
She got 7 years for the shop robbery, which is a fairly heavy sentence to what gets dished out these days. I pondered the notion that the judge may have 'upped' the sentence to take into account the fact that she got off the false improsonment charge.