A San Diego real estate agent has been sentenced to four years in prison after pleading guilty to helping launder money and falsifying loan documents to help a convicted marijuana trafficker purchase two homes, prosecutors said.In entering guilty pleas in March to two counts of money laundering, prosecutors said Marco Manuel Luis, 32, admitted that he was the real estate agent for Joshua John Hester. Hester pleaded guilty in January to conspiracy to distribute and manufacture marijuana and seven other charges related to a "grow house" in Rancho Santa Fe, Calif., and the operation of two medical marijuana dispensaries in San Diego.In his guilty plea, Luis admitted that he facilitated the purchase of the alleged grow house, located at 15702 Circo Diegueno in Rancho Santa Fe, for $...