PART 1: The Impossible Conviction
2018: The Conviction
Rajat Sharma is sentenced to life imprisonment based on irrefutable DNA evidence found at a murder scene. He screams his innocence, but "Science doesn't lie."
2025: The Ghost Returns
Seven years later, a new murder occurs. The DNA matches Rajat again. But Rajat is in a high-security prison under 24/7 surveillance.
PART 2: The Clue in the Scar
The Interrogation
Dr. Anjali notices a surgical scar on Rajat's hip. Rajat reveals he donated bone marrow to his estranged brother, Vikram, 10 years ago.
The Breakthrough
Dr. Anjali realizes the connection immediately. Bone marrow produces blood cells. If Rajat gave his marrow to Vikram, he gave him his DNA factory.
The Hunt
Police track down Vikram. He is alive, well, and the true killer.
PART 3: Anatomy of a Chimera
Mechanism: Engraftment
Vikram's own marrow was destroyed (Chemo/Radiation). Rajat's Stem Cells were introduced. They colonized the bone marrow.
The DNA Swap
Forensics extract DNA from White Blood Cells (WBCs). Since Vikram's WBCs are made by Rajat's stem cells, they carry Rajat's DNA.
Vikram is an Artificial Chimera.
- Blood DNA = Donor (Rajat)
- Skin/Organ DNA = Self (Vikram)
PART 4: Real World Cases
Case 1: The Semen Anomaly
Chris Long: After a transplant and vasectomy, his semen contained only his donor's DNA (via leukocytes in seminal fluid).
Case 2: Lydia Fairchild
Natural Chimerism: Lydia fused with her own twin in the womb. Her blood DNA didn't match her children, but her ovaries did!
PART 5: Resolution & Exam Summary
The Fix
To convict the right man, police used a Cheek Swab (Epithelial cells) instead of blood. The cheek swab matched Vikram 100%.
- Chimera: Two genotypes in one body.
- Forensic Marker: STR (Short Tandem Repeats).
- Tissue Specificity: Blood vs. Skin DNA can differ in transplant recipients.