The correct answer to this open question is the following.
I think that if President Johnson would have reacted sooner to what was going on in Mississippi, the three college students from the north might not have been murdered.
A more expedited action on the part of the federal government could have prevented the tragedy.
Let's have in mind that at that time, racism in Mississippi was a major problem in the state of Mississippi. The racist organization called the Ku Kux Klan aggressively attacked black people. Those were tense years in the southern states,
Thre young African Americans disappeared on June 21, 1964, close to Philadelphia, Mississippi. They worked as volunteers for CORE, the Congress of Racial Equality.
The federañ government presence was much needed to prevent e¿any calamity and aggression, and unfortunately, the help arrived late.