Timothy Jackson Jackson, 21 was formally charged with a total of 142 criminal counts

In pressing the case against Timothy Jackson , the man accused of one of the worst mass shootings in American history… prosecutors made it clear Monday they were leaving little to chance.

Jackson, 21 was formally charged with a total of 142 criminal counts β€” including two separate allegations of murder for each of the 12 people who died in the June 21 attack .

The two murder charges are based on different legal theories.