Witnesses before the grand jury, summoned to give evidence of any violation of the laws against gaming or lotteries, may be required to answer generally as to any such offense, within their knowledge, committed within the 12 months next preceding, without being first specially interrogated as to any particular offense; but no witness must be prosecuted for any offense as to which he testified before the grand jury, and any member of the grand jury may be a witness to prove that fact.
Ala. Code § 12-16-212 (1975)