judge george o'toole told jurors in the boston marathon bombing case they are not to attend this year 's race or related events .
the race takes place next monday , april 20 , and marks two years since dzhokhar tsarnaev and his brother planted two bombs at the finish line .
this as the the sentencing phase of the trial , in which witnesses will again be called to the stand , is expected begin next week and to take four weeks .
tsarnaev faces either life in prison or the death penalty .