The distance dependence of electron transfer (ET) rates between donors and accepters in a DNA environment has been an area of intense research and heated discussion, especially with regard to the recent report of ultrafast ET over a separation of >40 Angstrom. This paper is focused on quantitative modeling of the photodynamics and gel electrophoresis/photoclevage experiments of the untethered DNA/metallointercalator system. Simulations are compared to previously published experimental results in order to quantitatively examine the possible involvement of long-range ET and donor/acceptor clustering in the DNA-mediated ET between metallointercalators. Comparison of the simulation results with a broad range of experimental data strongly indicates that a fairly typical distance dependence for ET (beta approximate to 1 Angstrom(-1)) coupled to donor/acceptor clustering is able to account for all features in the data and for related photocleavage studies.