Which factors are needed to turn dead organism into fossil fuel?

To turn a dead organism into fossil fuel, three main factors are needed: 1) organic material from the dead organism, such as plants or animals, 2) high pressure from layers of sediment accumulating over time, and 3) high temperatures, typically from the Earth's heat and pressure from the overlying sediment. Over millions of years, these conditions transform the organic material into fossil fuels like coal, oil, or natural gas.