It happened on Sunday around 10:50 p.m. on the 4100 block of Old Mill Street.
Police say two brothers were involved in an altercation inside their home. During that altercation, 33-year-old Laurence Sullivan stabbed his 32-year-old brother Daniel multiple times.
Daniel Sullivan was transported to a nearby trauma center where he died shortly after. Laurence Sullivan was also treated for non-life-threatening injuries at a local hospital.
Laurence Sullivan was arrested by Irvine detectives on Monday and has been booked for murder. The cause of the conflict is still under investigation.