The cop's son, as correctly identified in the cast list, is played by Regis Toomey, not by "a very young William Holden" as stated by another viewer.
William Holden (I) (1918-1981) did not enter films until 1938.
The William Holden (II) in this film (1862-1932) is a much older character actor, who plays Inspector McArthur, and who is no relation to his better known latter day namesake.
Considering the six year gap between their two careers, there is really no reason to confuse the two actors.
For further information on Regis Toomey, consult his webpage.
William Holden (I) (1918-1981) did not enter films until 1938.
The William Holden (II) in this film (1862-1932) is a much older character actor, who plays Inspector McArthur, and who is no relation to his better known latter day namesake.
Considering the six year gap between their two careers, there is really no reason to confuse the two actors.
For further information on Regis Toomey, consult his webpage.