While it was never confirmed due to Frank Lundy’s death, various clues from Dexter hint that the FBI Agent secretly knew Dexter Morgan was the Bay Harbor Butcher. Considering Dexter had been moonlighting as the Bay Harbor Butcher for years without coming under any serious suspicion by his Miami Metro coworkers like Dexter's Angel Batista, Frank Lundy was his first true adversary to come close to exposing the truth. Dexter established that Lundy was an extremely talented agent with a reputation for solving seemingly impossible cases, but the series still sees the case “solved” without Lundy nabbing the real culprit right under his nose.
Just as Detective Joey Quinn stopped pursuing his suspicions of Dexter after entering a relationship with Deb, it seems the primary reason why Frank Lundy never pursued Dexter Morgan was because of his love for the character's foul-mouthed sister. Since Debra was closer to her brother Dexter than anyone else in her life, she could never be with someone who tried to pin him as a serial killer, even after she found out the horrifying truth for herself. Keith Carradine's Agent Frank Lundy seemed to have his suspicions of Dexter's protagonist early on in season 2, but pursuing him as a serious Bay Harbor Butcher suspect was dropped once Lundy began a romantic relationship with Deb.
Once Dexter had successfully framed Sergeant James Doakes as the Bay Harbor Butcher, Frank Lundy left town for his next case, with no further mention of being suspicious of Dexter. When Lundy returned to track down the Trinity Killer in Dexter season 4, he only briefly reunited with Deb and Dexter before being murdered by Trinity’s daughter Christine, thus leaving no concrete answer to whether he knew the true identity of the Bay Harbor Butcher. Of course, it can be argued that Lundy being such a noble FBI Agent means that he would never let a serial killer walk free, though there are still clues that he did know, but let his love for Dexter's Debra Morgan come before his moral duty. Here’s a breakdown of every clue that Lundy may have known Dexter was the Bay Harbor Butcher all along.
Lundy Hinted At Understanding Dexter’s Killing Motivations
Frank Lundy mentions to Dexter that the only excuse for killing is to save an innocent life, which is exactly the motivation for the Bay Harbor Butcher—or at least the moral code that Harry gave to Dexter. This Dexter season 2 line directed at Dexter himself hinted that Lundy knew he was the Bay Harbor Butcher, but may have believed what he was doing was a necessary evil. Lundy spent his life hunting serial killers in order to save lives, and although he wouldn’t kill a criminal himself unless absolutely necessary, Dexter is eliminating the murderers in a way that ensures they won’t be able to take any more innocent lives. Lundy is very by-the-books in the way that he operates, but he realizes that this also means many clues and pieces of evidence become unusable or formalities become hindrances. While he may not agree with the morality of the Bay Harbor Butcher’s actions, his line to Dexter suggests that he may hesitate to capture him as his work is needed. More than likely, however, Lundy’s principles about catching killers would still mean that he would pursue Dexter, even if he understood his reasoning.
He Called Out Dexter For His Sloppy Blood Work
This appears to be the most damning evidence that Lundy knew, or at least highly suspected, that Dexter was the real Bay Harbor Butcher. In Dexter’s season 2 episode “Morning Comes,” Lundy interviews Dexter about the “sloppy” blood work he did on Anthony Rodrigo’s case, which would have put him in jail had it not been proven wrong in court. Lundy then calls Dexter one of the “most cautious and precise forensics specialists” that he’s worked with, suspecting that he may have purposefully goofed the blood work to get Rodrigo off. Of course, this is exactly what Dexter did, as he wanted Rodrigo on the street so that he could kill the murderer himself. Dexter then gives unconvincing excuses about being overworked, though it’s clear that Lundy doesn’t believe him. Lundy never follows up on Dexter’s poor bloodwork, but it’s clear that at this point, the FBI Agent did suspect Dexter of purposefully botching the case, which is a clue that he could have been Dexter’s Bay Harbor Butcher.
Lundy Confronts Dexter About BHB In The Train Car
While the series is clearly framing the scene as Dexter fearing Lundy is on to him, the intelligence of Lundy still hints that he’s giving Dexter nods about his suspicions. When Lundy first walks up to Dexter, he asks him, “If you were the Bay Harbor Butcher, would you use a place like this?” Lundy then continues to closely monitor Dexter’s compulsive process as he sets up his kit, cleverly mentioning that the Bay Harbor Butcher would be compulsive and orderly. When Dexter agrees that the Bay Harbor Butcher likely never would have thought he’d be a role model, the look in Lundy’s eye hints that he suspects Dexter is talking about himself.
Lundy Knew Dexter Docked His Boat At Coral Cove Marina
One of the biggest breakthroughs in Dexter season 2’s Bay Harbor Butcher case was the discovery that the killer docked his boat at the Coral Cove Marina, which just so happened to be the home of Dexter’s boat, Slice of Life. To make the discovery even more significant, it was known that Coral Cove harbored many boats that belonged to those in law enforcement, which made it clearer that the killer was someone in or related to the department. Just after Lundy had slyly compared Dexter’s compulsions to that of the Bay Harbor Butcher, he quickly mentions that he’s hoping to get a new lead from the security cameras at the marina. Dexter then seems to be a bit worried, with Lundy then questioning Dexter about having a boat there himself. Even Dexter begins to wonder if Lundy had seen him on the marina’s security footage before he wiped it, believing that Lundy brought him to the crime scene that day in order to mess with his confidence.
Lundy Doubted Doakes Was The Bay Harbor Butcher
Although Lundy knew that the Bay Harbor Butcher was connected to law enforcement, particularly within Miami Metro, he still didn’t believe the suspect was James Doakes, even when the evidence was stacked against him. Maria LaGuerta continued to try proving that Doakes was innocent by verifying he was on a stake-out with her and even went to Haiti to have Dexter’s blood slides analyzed, but Lundy explained that because Maria violated protocol, he couldn’t use any of her evidence to exonerate Doakes. Dexter’s Frank Lundy even hinted that he believed Maria may be right about Doakes not being guilty, but had to follow police protocol in collecting evidence since he was a suspect. Sadly, by the time all of the planted evidence against Doakes was stacked up, there was no way that Lundy could relieve him of blame, even if he didn’t completely believe it to be true. Since Lundy doubted Doakes’ guilt as the Bay Harbor Butcher, the only other suspect that would make sense at Miami Metro is Dexter Morgan, suggesting he had to be Lundy’s own prime suspect.
Lundy May Have Hoped Dexter Would Finally Find & Kill Trinity
While Frank Lundy was absent for Dexter season 3, he returned to Miami in the season 4 premiere to recruit Miami Metro’s help in solving the Trinity Killer case, which the FBI believed to be a wild goose chase. While personally investigating the case, Lundy frequently requested the help of Dexter’s blood work and judgment, with certain lines by the FBI Agent continuing to suggest he knew about Dexter’s serial killing hobby. After Trinity murders Lisa Bell in Dexter season 4, episode 2, Lundy tells Dexter that it was “Kismet” because if Trinity had struck elsewhere he wouldn’t have had access to a blood analyst “of his caliber…” with a long, purposeful pause before “caliber” that hints at the true nature of Dexter’s blood obsession.
Lundy’s work with Michael C. Hall’s character in Dexter season 4 frequently hinted at being grateful that John Lithgow's Trinity Killer was working in Miami because Dexter could help to finally catch him. Since Lundy considers Trinity the worst killer he’s ever faced, he may have wanted Dexter’s help, specifically, in hopes that he would murder Trinity as the Bay Harbor Butcher, ensuring that he could never kill again. The proper avenue of going through the FBI and law enforcement hadn’t worked for Lundy over the past several decades, so after he retired, he likely sought out Dexter Morgan in order to finally take out Trinity for good.
While Lundy never had any proof of Dexter being the Bay Harbor Butcher, he clearly knew that Dexter’s blood skills went further than his analysis work at Miami Metro. Sadly, Frank Lundy would be murdered in Dexter season 4 before seeing Trinity’s murderous spree finally come to an end at the hands of Miami Metro’s skilled “blood guy.” If Dexter: New Blood's Angela could come to the conclusion that Dexter was the Bay Harbor Butcher with her lackluster evidence, it’s highly unlikely that professional serial-killer hunter and FBI Agent Frank Lundy didn’t secretly know as well.