Officers said 33-year-old Patrick Allen French of Costa Mesa shot his ex-girlfriend Wednesday morning and then took off in a rented Ford Explorer.
The victim suffered from multiple gunshot wounds and was rushed to the hospital in serious condition.
A manhunt was launched for French, saying he was considered armed and dangerous.
But his body and his car were discovered late Sunday in San Diego. Police believe he took his own life.
His ex-girlfriend remains in the hospital in stable condition.