- The team has to look into the death of a baby that had been left inside of a car during a heatwave. During the investigation, they discover that the parents had already lost a child to a genetic disease/disorder that he had inherited from them and that their current child was starting to display the same symptoms. Unwilling to go through the pain of watching another child suffer and die, the parents came up with the plan to put their baby to sleep and leave him in the car. The worse part of all this? The baby was actually having a bad reaction to the fertilizer the wife was using in her gardening business and coming home with traces of it on her. If they had just waited a few days for the test results to come back they would've known this. As Catherine put it: "[They] killed a perfectly healthy baby." Their reaction to this revelation is absolutely heartrending.
- This is actually one of the better CSI episodes, because unlike most others, where the motive of death is rather upsetting and disturbing, the motive for infanticide here was actually done from an act of pure love not spite. The couple deliberately killed their child, not because they wanted him dead, not because they rendered him a nuisance, but because they thought he was going to die. This is not that dissimilar to a pet owner wanting to euthanize their pet, thinking that they are going to die, but unbeknownst to them their illness is not an actual terminal disease. As the father put it (who was more responsible for the death of the infant), he was not a bad parent, but just negligent, he probably meant the same for the mother. At the end, as much as you want to condemn the parents for their horrendous act, you cannot help but feel sorry for them, because they actually cared about their child.
- Grissom's speech to the killer in Butterflied. After four seasons, it was finally confirmed that he was romantically interested in Sara, he was just too afraid to do anything about it.Grissom: It's sad, isn't it, doc? Guys like us. Couple of middle-aged men who've allowed their work to consume their lives. The only time we ever touch other people is when we're wearing our latex gloves. We wake up one day and realize that for fifty years we haven't really lived at all. But then, all of a sudden we get a second chance. Somebody young and beautiful shows up. Somebody ... we could care about. She offers us a new life with her. But we have a big decision to make, right? Because we have to risk everything we've worked for in order to have her. I couldn't do it. But you did. You risked it all. And she showed you a wonderful life, didn't she? But then she took it away and gave it to somebody else...and you were lost.
- Grissom's horrified realisation of why Sara has been abducted by the Miniature Killer.Grissom: This girl holds me responsible for the death of Ernie Dell. I took away the only person she ever loved, so she's gonna do the same thing to me.
- In the episode "Harvest", a young man, Daniel, is dying of leukemia, and surviving thanks to bone marrow transplants and blood transfusions from his younger sister, Alicia. He can't stand seeing her suffer for his sake, so he asks his parents to stop, but they refuse after his kidneys start to fail. Daniel ends up poisoning Alicia so she wouldn't suffer any more. Grissom points out he'll be arrested for murder, but Daniel only has six months to live so he won't even survive to see the trial.Grissom: This wasn't a mercy killing, Daniel. This was an execution. Bone marrow, transfusions... that's her blood in your veins. It dripped out of your nose onto the blanket while you were killing her. If you cared so much for Alicia, why didn't you take your own life instead of hers?Daniel: Suicide isn't an option. It's an unforgivable sin in the eyes of God.Grissom: But you believe that your God forgives murder? If that's your defense, it won't keep you out of jail.Daniel: But my death will. See, I've got about six more months. I'll be dead before there's even a trial. I... I do want to thank you, though.Grissom: For what?Daniel: For speaking for Alicia. You're probably the first person in her life to think only of her. You know, you may not believe in God, sir, but you do his work.
- The Death of Warrick Brown in the first episode of Season 9. Everyone is falling apart and saddened by the loss of their comrade, and Grissom wanted to hold him tight enough to keep him alive. It was a tragic loss with how everyone was dealing with it.
- The video game Deadly Intent references this with the player character being compared positively to Warrick; most fans would find themselves stabbed in the feels when the comparison is made.
- In "Say Uncle", Grissom investigates a double homicide where a Korean man and woman apparently killed each other. It's revealed the woman has an eight-year-old son, Park, who watched her shoot the man, who turns out to be Park's uncle, who was recently released from prison. He and Park's deceased father were gangsters, and it also comes to light that both Park and his mother, who was a junkie, are HIV positive. Park's mother put him in a medically unsound, and painful, clinical trial, with his doctor giving him a gastric bypass tube. When Park's uncle found out about this, he tried to take Park away from his mother, who hunted them down and shot the uncle... Then Park, driven over the Despair Event Horizon, took his uncle's gun and shot his own mother to death. As Brass puts it, Park didn't have any control over his own life until he picked up that gun, and the episode closes with an eight-year-old boy going off to juvenile detention. It's not often a CSI regrets solving a case, but in this episode, it's easy to see why Grissom is so deeply affected.
- Jim learning his daughter was a murderer. When she confronts him, he says she can she shoot. He's already dead inside.
- The very end of "Cold Blooded", where Carly Beck finally gets closure over her missing daughter.
- "Friends & Lovers" details the mystery of a young man by the name of Eric found naked and smothered to death in the middle of the desert. As it turns out, he and his best friend Bobby Taylor attended a concert, where they ingested hallucinogens and experienced a very bad trip. Bobby, suffering from auditory hallucinations caused by the music and Eric's screaming, accidentally smothered Eric to death trying to make it stop. Upon revealing this to Bobby, the poor man is devastated, and, when his lawyer tries to convince him to plead on diminished capacity, he has but this to say:Bobby Taylor: You don't understand...I don't care what happens to me. I killed my best friend.
- This case, like the previous, hits Grissom hard, and after Bobby is booked, he goes to an amusement park and boards the roller coaster, not to enjoy himself, but to clear his head. His stony, intense expression as the roller coaster rockets through the course makes it clear how deeply cases like this affect him, how much he wishes he could just forget it and leave it all behind, but he can't. He won't.
Tear Jerker / CSI