Suisham missed a chance to put Washington up 10 points with less than two minutes left. Saints quarterback Drew Brees then carved up the Redskins secondary for 80 yards in 33 seconds to send the game into overtime.
Garrett Hartley's 18-yard field goal kept the Saints perfect.
The win also clinched the NFC South title. It is the Saints' second title in four years and third this decade, but just their fourth in franchise history. New Orleans won its first division title in 1991.
The Saints' 12th regular season win ties a team record. They also won 12 games in 1987 and 1992. While the Saints record remains perfect, New Orleans played a far from perfect game.
Here's a look at the good, the bad, and the ugly from Week 13.
Despite looking uncomfortable all day long, Brees still managed to throw for over 400 yards and two touchdowns.
Hartley hit four field goals, including the game-winner, in his first game of the season.
Robert Meachem caught a career-high eight passes for 142 yards and one touchdown. He also scored a touchdown on a fumble recovery after Brees threw and interception.
Jonathan Vilma's interception ended the Redskins' hopes of winning the game in regulation.
The Saints committed seven penalties for 102 yards while the Redskins committed just two for 15 yards. Forty-seven of those penalty yards came on the Redskins' first drive, which resulted in a touchdown.
Malcolm Jenkins looked like the rookie he is six days after blanketing Wes Welker. Jenkins got burned several times by Santana Moss, Antwaan Randle El, and Devin Thomas.
New Orleans hardly got any pressure on Jason Campbell and did not record a sack.
The Saints' running game managed just 2.3 yards per carry, forcing Brees to throw the ball nearly 50 times.
The injured cornerbacks need to come back soon. Jabari Greer, Randall Gay, and Tracy Porter were all inactive and Jason Campbell threw for over 350 yards and three touchdowns.
A Look Ahead
New Orleans has four games remaining in the regular season and must continue winning to secure home-field advantage.