Weiss became the main antagonist in Dexter by Design.
After four bodies appeared in one day, staged in some form of modern art, Dexter is puzzled why is his Dark Passenger doesn't have any idea about it. As the bodies are some twisted interpretation of tourist attraction, Dexter and Deborah visited The Greater Miami Convention and Visitor's Bureau and find out that they were supposed to be harmed by attacks in the first place as they have a DVD sent to them which depcits what is supposed to be murders as well as people reacting to them in the fashion of tourist commercials.
After picking up a list of recently fired people as their suspects, they visit a few of them and then they have an argument about Dexter being a serial killer. Because of that, when they visit yet another suspect, a Canadian citizen who used to work as a writer for bureau before getting fired and even removed by security from the place, Dexter remains in the car. Meanwhile, after showing her badge, Deborah gets stabbed. Dexter catches a man who is supposed to be an attempted murderer, Alex Doncevic, but his lawyer, Simeon has him freed.
Nearly improvising, Dexter kills Doncevic the same night using the instruments he supposedly used to kill his victims, especially surgical saw.
It later turns out that Doncevic wasn't the killer and wasn't even an attempted murderer - the four bodies were stolen from the morgue and the knife which was used to stab Deborah had other thumbprints on it, probably those of Weiss.
But before Dexter finds anything on Weiss, Weiss himself sends him an e-mail with a link to YouTube video which depicts... Dexter (filmed from the back with his face not seen) killing Doncevic. Another videos on Weiss channel are the same three "commercials" that were sent to bureau and a mysterious fifth video. But Dexter has no time to watch it as ther's fifth decorated body.
This time it's a real murder and Dexter recognizes the body - it's Robert Deutch, Cub Scouts den leader whom he had seen while Cody joined Cub Scouts as a part of his training to keep the facade of an ordinary kid. It's obvious that Weiss followed Dexter and murder was a message to Dexter. Dexter sees the car leaving the crime scene, after driver had filmed it.
He checks the car in the database and it turns out that it belongs to a video editor named Kenneth Wimble. Dexter goes to his house only to nearly being killed in it's explosion as Wimble does. Before the explosion there is a sound of a scream that Weis is edited in every of his videos.
Having a concussion, Dexter forgets about fifth video for some time but later remembers it and watches. It is a message, recorded by Weiss to Dexter himself in which Weiss explains that not only Doncevic was his lover, he was also the only thing that kept him from killing, and it was his idea to use bodies from the morgue. Dexter remebers that there was a gay couple with cameras at least on the two of crime scenes and identifies them as Doncevic and Weiss. As Brandon is a killer now, Dexter's Dark Passenger is much more helpful and predicts his next step - to kidnap Cody and Astor as a revenge for killing Doncevic.
Dexter fails to prevent an attempt because he mistakes a school gate repairman for Weiss while real Weiss stages a car crash with Rita to kidnap the children. Bernard, still was not ready for children to attack him in turn and barely escapes being beaten and having a pencil stuck in his foot.
Because of attempted kidnapping, Dexter has all kinds of problems - FBI Special Agent Recht, cops guarding his house, Sergeant Doakes, Detective Coulter, Captain Matthews's superior Israel Salguero and, of course, Weiss himself. He also has Weiss' sketch book which reveals his grand plan - to manipulate the video of Doncevic murder so that Dexter's face was visible (even if it requires Photoshop) and to project it on the wall of hotel called the Breakers in Palm Beach.
Trying to get a help from Deborah's boyfriend Kyle Chutsky, Dexter is startled that it's not The Breakers, but a hotel named Hotel Nacional, in Havana, Cuba, where a huge modern art festival will be in a few days. At first being reluctant to help Decter, Kyle agrees when Deborah awakes from coma and asks Dexter to kill Weiss.
Using fake identities of Baptist Brethren International Ministries priests, Dexter and Kyle get to Cuba, check in Hotel Nacional and wait for Weiss to show up (to make sure they will know they say to Kyle's associate Rigelio who works in the hotel that it's Bernard's birthday and they want to have a surprise for him). After waiting for two days with two Walther handguns bought locally, Dexter and Chutsky were surprised themselves with Rogelio strangled by the belt and being at their door. With Weiss being obviously ahead of them Dexter and Kyle escape to Miami using two other fake passports.
Being cornered by Coulter on his activities, Dexter is forced to say to him what Weiss eventually plans, especially when the next YouTube video, Dexterama has Rita bound. Coulter informs Dexter that there's an art festival on it's own in Miami - The Art-stravaganza, at the Convention Center. Both Coulter and Dexter separately go there, Dexter having Cody and Astor with him as "witnesses" (Cody requests for some kind of weapon and gets a screwdriver).
They find Rita bound and nearly cut with a table saw as a part of installation named “Who Can Save Our Nell?” with a "Please do not disturb the performers" sign near. While Astor and Cody are trying to save "Nell" much to crowd's dismay, Weiss strangles Dexter with a fishing line till he's barely concious and then starts to film the event, trying, on the other hand, to stop Cody and Astor from saving their mother. He nearly succeeds, knocks children on the floor and even tries to kill them with a screwdriver, but Rita who has her legs free at the time kicks him twice with her legs into the table saw, which cuts his arm off.
In the epilogue, Dexter says that paramedics weren't able to save Weiss and he bled to death, while still having his dream of drawing attention in the modern art circles come true, as Dr. Elaine Donazetti, a critic and a very important figure in the world of contemporary art has his performances described in her books.
It seems that Isaak Sirko was based partially on Weiss, as Dexter kills his lover.
- Roger Deutch - made into a tableau in the same style as four stolen victims before - intensities removed and replaced with various objects associated with Cub Scouts, plastic mask with a smile glued to face.
- Kenneth Wimble - exploded in his own house using a propane canister.
- Rogelio - strangled with a belt.
- Detective Coulter - strangled with a fishing line and propped up in a corner of “Who Can Save Our Nell?” performance (with a sign "Semi-conductor"), dressed in an old-fashioned conductor's hat and with heavy electric cable was attached to his arms by large, jumper-cable clips.
- Four Staged Bodies - were believed to be victims until it was found out that they were stolen from the morgue.
- Alex Doncevic - is probably officially counted as a victim of Weiss because there was no solid evidence that Dexter did that. It is believed that Doncevic tried to leave Weiss and that's why he killed him and blamed Dexter not for the actual kill, but for whole situation.