Deadlocks can happen at anytime and processes compete for locks, threads, memory or other shareable resources. SQL server periodically detected deadlocks and kill one of the blocking one as victim. In many cases, we want to know the processes involved in order to eliminate or reduce the deadlock conditions.
Here is a step by step instruction on how to capture the deadlocks with Microsoft SQL Server Management Studio.
Once you have deadlocks captured, you can open and view the graphs by File->Open from SQL Profiler.