The coroner concluded that she had likely been dead "4 to 7 days prior to recovery, and he theorized that she had been alive 10-14 days after her abduction". She was abducted on Wednesday December 10th 1969 and found at Bolinas Lagoon on December 28th 1969, so that places her murder between December 20th 1969 and December 24th 1969, allowing for a small margin of error. The longer between death and discovery, the more difficult it is to make an accurate determination.
The phrases on the Cancer and Leo communications are difficult to interpret, but when we consider the random phrase of "BIRDS FLY SOUTH" (pasted between the 18th and 24th) and the location where her body was discovered, on a north to south Pacific Flyway for migratory birds, one can't help thinking that the pasted clues were cryptic in nature. Irrespective of their correct meanings or otherwise, the "forecast" letters and the timing of Leona Roberts abduction should not be overlooked. It is likely only one person knew the day-by-day forecast for Leona Roberts, and his identity remains a mystery to this day.