Police arrested 47-year-old Lee Bell yesterday in suspicion of murdering Pearla Louis, the 52-year-old woman who was found in a suitcase in the bay last month. Louis' family said she and Bell had had a relationship, and Bell had been accused of abusing Louis in the past. The cause of death and motive have not been released. Bell was already in San Francisco County Jail at the time of his arrest for probation violation.