Running this script will tell you which instance of a process is using lots of CPU on the database server. You can use the loginame or hostname columns to identify the person.
SELECT TOP 25
spid
,blocked
,convert(varchar(10),db_name(dbid)) as DBName
,cpu
,datediff(second,login_time, getdate()) as Secs
,convert(float, cpu / datediff(second,login_time, getdate())) as PScore
,convert(varchar(16), hostname) as Host
,convert(varchar(50), program_name) as Program
,convert(varchar(20), loginame) as Login
FROM master..sysprocesses
WHERE datediff(second,login_time, getdate()) > 0 and spid > 50
ORDER BY pscore desc