Jim Pharr teaches that unusual patterns are often great clues to investigate a fire. In this example, there is a doughnut pattern that was caused by air movement and sooting. In the center, there was not enough air to combust the ignitable liquid, which resulted in less burning in that location. Also, be on the lookout for the pooling of liquids and the patterns created from this occurrence. Be careful stating that there was a flammable or combustible liquid present until the lab verifies a sample – you could very easily be mistaken.