The Team Bondi head explained how the small studio's ambition saw development go on for seven years.
"One [thing] is the size, it's a huge game - probably too big. The map's massive, and so that's probably my fault," he told Official PlayStation Magazine.
"We had to build a new process to do that. We were a brand-new studio - we had brand-new tools, new technology. We have tools that allow you to build cities now, but we had to build that kind of stuff and make it work.
© Rockstar Games
"Everything from the road network, where all the trolley cars go, all the cables connecting automatically to all of the buildings."
McNamara continued: "The tech was pretty extensive, including MotionScan. I'd say the first year and a half - [maybe] even longer - was just research. Newspaper research, guys going over to LA and doing research on the buildings, taking photos, getting all the resources together.
"We were quite a small studio - 16 people or something – and we had to have all this material so we could start building stuff."
McNamara recently explained why protagonist Cole Phelps would often provide over-the-top responses in interrogation scenes.
L.A. Noire placed fourth in Digital Spy's Games of 2011 countdown.
The L.A. Noire: Complete Collection, which features the original game and all DLC, is out on Xbox 360, PlayStation 3, PC and OnLive.
> Read Digital Spy's Xbox 360 review of L.A. Noire
Watch the launch trailer for L.A. Noire below:
