in a compounded tense (auxiliary + past participle) the past participle agreed with the object pronoun in the case that a direct object pronoun in the third person singular and plural (la, lo, li,. le) is used. (in the other cases (mi, ti, vi,ci) the agreement is optional and nearly never used.
So in this case the l' has to be a la and not a lo
l'abbia presa = la abbia presa
l'abbia preso = lo abbia preso
Sandrabruck: You are obviously skilled at Italian. Would an Italian recognize, in ordinary oral conversation, that a mistake had been made if "preso" had been used instead of "presa"? (This type of question arises frequently, but this is as good an opportunity to pursue it as any.)
Do Italians "pick-up" women at bars, museums, etc., as Americans use that term (to meet someone knew and establish some sort of relationship, however fleeting).
Do Italians refer to abductions or kidnappings as "being taken"?
Either would make "her" quite appropriate here.
I'll split the difference with you. First, my sentence has nothing to do with what I will find out in the future; "will" has no future meaning here - "will have" is simply being used to talk about something we are pretty sure happened in the past, just as we use "must have" and "can't have" to speculate about the past:
"We can also use will have to 'predict the present' - to say what we think or guess has probably happened - It's no use phoning - he'll have left by now. " Practical English Usage, Michael Swan.
But I agree that it is perhaps adding a particular point of view rather than being a simple statement, as in "that he's taken it". I am suggesting, perhaps, that he's not the type to take it.
Despite the explanations above, which if there is a thread that leads me to "presa" I can not see it, there is no indication in "I do not think he has taken it" whether the "it" is masculine or feminine. Therefore my translation ending in "preso" is just as correct as the one ending in "presa"