In chapter 5 of Of Mice and Men, why does George leave the barn where the corpse of Curley's wife lies, and then return to it with the other men?

Dead puppy in hand, the panic-stricken Lennie flees the barn,
leaving the hay-covered corpse of Curley's wife whom he has unintentionally shaken to death. A
few minutes later, Candy discovers the body, summons George, and with him discusses what they
should do.  Burdened by the consciousness of his shattered dreams, George nevertheless comes up
with a plan of action: Candy is to spread the word of the death to the other men, but to pretend
that George was not present for the initial discovery of the body. George leaves, but in a few
moments - secretly armed with Carlson's Luger - returns to the barn in the company of the men
Candy has ushered in. Thus, he is present to mislead the posse an enraged Curley has put
together. The vigilantes head south, but George makes his way to the spot on the Salinas River
where in Chapter One he had instructed Lennie to return in the event he got into any
"trouble". With George's skillful handling of the catastrophe, the plot lines of Steinbeck's
tragedy begin to converge. Curley, vicious and vengeful; the migrant workers, lonely and
shiftless; Carlson, who would callously shoot both dog and man; Slim, a prince of compassion;
and, finally, George, the man who loved Lennie enough to put him to death meet on the bank of a
river across which rise the Galiban mountains, symbol of the promised land the two men will never
enter.