The missing mother
Death is symbolized by an absent mother in this novel. In this case, she is missing because she has literally died, but the symbolism is more nuanced than just that detail. For instance, the mother's missing insight leaves Gerry in a new dynamic with his daughter. Gerry does not have Donna to help mitigate that intimacy, and in light of the agony of Donna's death, the two are in a new chaotic experience as father and daughter, and as co-survivors of a painful family death.
The police as symbolism
One can easily see the police visit as a symbolic moment. The police are symbols of human power, so when they fail to solve the double homicide, that suggests that all the human power in the world cannot solve the riddle of death. It also is a poignant reminder that if not for human death, there might not be any police at all. Police exist because people are willing to collaborate in community for the purpose of staving off human death. Often, people forget that, but it is not easily forgotten when the police are at one's house investigating a murder.
The symbolism of death and rape
Content warning: this novel is fairly graphic and so is this portion of the analysis. Jessica is a social worker, which basically implies that her job is being exposed to human suffering in all its varieties. Her quest to discover the riddle of death that has plagued her family coincides with the discovery of the victims' lives. She learns that the victims of the murder were also the victims of rape. This is symbolic in an important way. One can say this symbolizes the other side of the death conundrum: why should life be so filled with suffering if we all just die in the end? That is the question in the symbol.
The father-daughter pair
Two Jessica, Gerry is strange now, because it was always "Mom and Dad," to Jessica, but now he is obviously Gerry. Now that death has broken the delusional spell in Jessica's mind which made her believe subconsciously that her parents were immortal, she is simultaneously awakened to the same truth about her father. Now her father is weakened by serious bereavement, and to make matters worse, the father has the archetypal nightmare of seeing his dead wife in his daughter's mannerisms and appearance.
The abrupt ending
The novel has the genre feel of a murder-mystery, like a "Who-Dunnit"-style mystery, but in the end, without any resolution, the novel just ends. This whole novel takes place in the domain of chaos. Jessica strives in vane for answers that do not provide catharsis; every discovery makes the weight of untimely death even harder for her to bear in her mind. At the end, when the reader says, "Wait, no, where's the answer to the riddle?" that is symbolic, because that is the appropriate response to the novel's topic: death. The ending is a punchline for the novel, as if the novelist has turned to the reader and said, "Well don't ask me for the answer! I'm in the same boat as you!"
