First, some historical background:
The Greek translation of the Old Testament (called the Septuagint or LXX - 'the 70'):
as handed down through Christians contains 14 (or 15 depending how they are grouped) additional books not found in the Hebrew Old Testament. These additional books are know by the Greek term apocrypha, meaning "hidden."
http://www.bibleteachings.org/apocrypha.html
The Catholic Bible contains 11 of these books. It is important to understand that the majority of these writings are certain to have been around during the life of Christ and certainly the Apostles were aware of them (we see their influence in the NT - see Jude for example. NOTE: quotation in scripture does not equal canonicity, Paul quoted from pagan poets.)
Second, regarding the Hebrew Old Testament:
What protestants call the "Old Testament" comes from the Hebrew "Tanakh". The same books occur as are in the Old Testament (sans Apocrypha). But that's not the issue. What is pertinent to our discussion is the order of the books in the Hebrew Tanakh: There are three divisions: The Law, the Prophets, and the Writings. (Stay with me! it gets good.) In the Protestant Old Testament, The Order is Law, Writings, Prophets (the last being Malachi). However, in the Tanakh, it is Law, Prophets, Writings. Which means that The first book is Genesis, but the last book (contained in the writings) is Chronicles.(here for verification.)
Key here is that the Apocrypha was tagged on to the end of the OT.
Finally, lets tie it together:
Matthew 23:35-35
Therefore I send you prophets and wise men and scribes, some of whom you will kill and crucify, and some you will flog in your synagogues and persecute from town to town, so that on you may come all the righteous blood shed on earth, from the blood of innocent Abel to the blood of Zechariah the son of Barachiah, whom you murdered between the sanctuary and the altar.
Jesus is speaking here about the of the historic rejection of the prophets. Then he makes a comprehensive statement - about the blood of all the righteous shed on the earth. And for this he refers to the Hebrew scriptures and starts with the first innocent who was murdered (Abel - from Genesis, the first book). The next name would be the last prophet, we assume. But who's this Zechariah fellow? He's not Zechariah the prophet of the eponymous book that's almost at the end of the OT. It's better than that. You know where I'm going, but you're not sure...
2 Chronicles 24:20-21
Then the Spirit of God clothed Zechariah the son of Jehoiada the priest, and he stood above the people, and said to them, “Thus says God, ‘Why do you break the commandments of the Lord, so that you cannot prosper? Because you have forsaken the Lord, he has forsaken you.’” But they conspired against him, and by command of the king they stoned him with stones in the court of the house of the Lord.
A murdered prophet. To a modern day Bible reader the connection would not have been made. But hopefully it's clear now - Christ was referring to an incident from the last book of the Tanakh! With his sweeping statement, he was referring to all of scripture - from the beginning with Abel, to the end, with Zechariah. And there's no mention of that group of documents which rhymes with "Apocrypha". Seems pretty clear that he didn't consider them at all. So why should we?
[For even more clarity, See also: Luke 24:27,44 "law, prophets, writings". No Apocrypha.]
Remember: they existed in practically their full state at that time. It wasn't like the New Testament, which hadn't been written yet.
