Pacer Sylvester Louis fully utilised helpful bowling conditions to leave Banks in danger of suffering an innings defeat.
A shower half-an-hour into the day's play transformed a firm pitch into a batsman's nightmare, and Louis, almost unplayable sometimes, completed a haul of eight for 23. He claimed five for 22 in the first and three for one in the second innings.
Louis held such a vice-like grip over the batsmen that at one stage in the second innings he had three for nought.
Banks now need another 163 runs to make Police bat again, a difficult task whatever the conditions on Saturday.
Scoring at almost a run-a-minute, Banks reached 29 for the loss of Mike Maynard before a heavy shower drove the players from the field.
Tea was taken early and when play resumed, with 70 minutes lost, Louis immediately replaced Duane Davis and the horrific ordeal started for Banks.
Louis, with able assistance from medium-pacer Alvin Campbell (three for eight), washed away the remaining eight wickets for 47 runs.
Banks batted one player short as Henry Austin was absent. Their problems were further complicated by a finger injury to Barry Callender on the opening day. He made 12 before he was caught by Clarke at forward short-leg off Louis. Sean Armstrong topscored with 18.
Louis' eight-wicket haul pushed his tally to 57 wickets for the season. His team-mate Emmerson Sealy has 51.
When Police enforced the follow-on Banks' innings started with high drama as the first two wickets fell before a run had been scored. Armstrong was bowled by Louis and Richard Carter was pouched by Rudolf Clarke at forward short leg, also off Louis. Stand-in opener Winston Reid was trapped leg-before to Louis with the score on five.
In other matches:
St. Catherine vs Carlton: St. Catherine 123; Calrton 145
Wanderers vs Empire: Wanderers 84 and 83/4; Empire 150/4
declared
Spartan vs Schools North: Spartan 86 and 98/7; Schools North 123
Maple vs YMPC: Maple 143 and 17/1; YMPC 75
BET vs Schools South: 184-6 declared and 88/2 declared; Schools
South 60 and 36/1
BCL vs Pickwick: BCL 131 and 0/0; Pickwick 136