Lethal 1.0 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. The program belongs to Multimedia Tools. The actual developer of the program is Lethal Audio.
From the developer:
Lethal is a software synthesizer plug-in in VST, AU, and AAX formats. It features a 5GB library of commercial quality sounds; over 1100 instruments & presets, and 2140 percussion & drum samples are present. Lethal is compatible with any DAW software that accepts VST, AU, or AAX plugins.
You may want to check out more software, such as Lethal League, Conspiracies II - Lethal Networks or Void War, which might be related to Lethal.