During my PhD thesis research (1946-1949), I explored the effects of light on the uptake of (32)P-labeled inorganic phosphate (P(i)) by cells of photosynthetic bacteria and microalgae, and the dynamics of P turnover between low and high molecular weight cell constituents. The results were interpreted as evidence for the conversion of light energy to the chemical energy of phosphorylated compounds. The experimental results also suggested to me that the precursors of the P in DNA bacteriophages of Escherichia coli must be low molecular weight phosphorylated compounds present within the host cells and led to the design of an experiment to determine the conservation of (32)P of an infecting phage particle in its numerous progeny. The experiment envisaged was never conducted because phage labeled with (32)P of high specific activity showed unexpected loss of viability. Thus, by serendipity, 'suicide' of phage due to (32)P-beta decay was discovered. (32)P-decay 'suicide' provided a technique that was useful for analysis of phage genetic structure and replication. This memoir describes the unusual circumstances leading to the decisive role of serendipity in revealing an extraordinary phenomenon.