Overview of the relief carving on Panel 4.
No evidence is available for this source.
Panel 4 has a much more open composition than the other three. On Panels 1-3 the sculptor's pick is used but on Panel 4 a tooth chisel is more common (or used in the same place). This suggests a different carver, or team of carvers, working on the figures at least. Other source images documenting the block sizes (PR500_05_17) and toolmarks (PR500_06_07) on this panel are available.