(from the http://www.bibleinfo.com/en/questions/who-were-twelve-disciples webpage)
Matthew, or Levi, son of Alpheus, lived in Capernaum. He was a publican or tax collector. He wrote the Gospel that bears his name. He died a martyr in Ethiopia.
The call of Matthew to the apostolic band is mentioned in Mark 2:14, Matthew 9:9; and Luke 5:27-28. From these passages, we learn that Matthew also was called Levi. It was a common custom in the Middle East at the time of Christ for men to have two names. Matthew's names mean "a gift of God." The name Levi could have been given to him by Jesus. It is likely that James the lesser, who was one of the twelve Apostles, was Matthew's brother, also the son of Alpheus. Although we know little about Matthew personally, the outstanding fact about him is that he was a tax collector. The King James Version calls him a publican, which in Latin is Publicanus, meaning engaged in public service, a man who handled public money, or a tax gatherer.
Of all the nations in the world, the Jews were the most vigorous haters of tax gatherers. To the devout Jew, God was the only one to whom it was right to pay tribute in taxes. To pay it to anyone else was to infringe on the rights of God. The tax collectors were hated not on religious grounds only but because most of them were notoriously unjust.
In the minds of many honest, Jewish men, these tax collectors were regarded as criminals. In New Testament times they were classified with harlots, Gentiles and sinners (Matthew 18:17; Matthew 21:31, 33; Matthew 9;10; Mark 2:15,16; Luke 5:30). Tax collectors had been known to assess duty payable at impossible sums and then offer to lend the money to travelers at a high rate of interest. Such was Matthew. Yet, Jesus chose a man all men hated and made him one of His men. It took Jesus Christ to see the potential in the tax collector of Capernaum.
Matthew was unlike the other Apostles, who were all fishermen. He could use a pen, and by his pen he became the first man to present to the world, in the Hebrew language, an account of the teaching of Jesus. It is clearly impossible to estimate the debt that Christianity owes to this despised tax gatherer. The average man would have thought it impossible to reform Matthew, but to God all things are possible. Matthew became the first man to write down the teachings of Jesus. He was a missionary of the Gospel, who laid down his life for the faith of his Master.
The apostolic symbol of Matthew is three money bags which reminds us that he was a tax collector before Jesus called him.