The Sunday graduation exercises at the University of Richmond were more somber than usual. They took place one day after students and professors learned two UR alumni were killed in a hot air balloon crash in Caroline County. The victims included Ginny Doyle and Natalie Lewis, who worked for the Lady Spiders’ basketball program. Pilot Dan Kirk also died after the balloon crashed to earth Friday night near Doswell. The Federal Aviation Administration and the National Transportation Safety Board are also investigating the crash.