In today's fractured literary marketplace, there are as many ways to write mystery novels as there are quirky names for fictional detectives. Publishers and agents group mysteries in categories with names such as "culinary," "cozy," "historical," "classic whodunit" and "women in peril."

But perhaps an overarching distinction is the one between mysteries that focus on characters and their psychodramas and ones that focus on, well, the mystery. Agatha Christie excelled at the latter type, creating ingenious puzzles. The other, character-driven mystery, is exemplified by the British TV series "Prime Suspect," whose creators seem to be more interested in dissecting the gender politics of a police station and the personal conflicts of their heroine than in obscuring the killer's identity in a heap of false leads.

With Still as Death, the fourth novel in her Boston-based Sweeney St. George series, Hartland author Sarah Stewart Taylor makes it clearer than ever that her mysteries fall in the "character-driven serial" group. As a puzzle, Still as Death doesn't satisfy. It offers more substance as a chapter in the ongoing saga of Sweeney St. George - a young art history professor with family baggage - and her friend Tim Quinn of the Cambridge Police Department.

As the novel opens, Sweeney, who studies the "art of death," has finally assembled a triumphant exhibit of her discoveries, which range from eerie Victorian postmortem photographs to contemporary gang-land memorial decals. When the exhibition's opening at the Hapner Museum is interrupted by a murder, linked to the attempted theft of an ancient Egyptian artifact, Sweeney's informal investigation takes her back in the museum's history.

The theft may be related to a successful heist in 1979, also involving Egyptian antiquities, that was witnessed by an undergraduate named Karen Philips. Karen committed suicide just months afterward, and Sweeney wants to know why. Was the young woman's death related to the theft? To her involvement in a radical campus feminist group, which is now helmed by one of Sweeney's colleagues? To her interest in a particularly beautiful funerary collar that appears to have disappeared from the museum's collection?

As Sweeney and Detective Quinn take their separate paths to investigate the murder, Taylor knocks down red herrings one by one. The museum staff offers a full cast of suspicious characters, from the arrogant curator and his toadying second-in-command to the gadfly feminist professor who sleeps with her students.

But the subplots are where the action is. One of them involves Sweeney's relationship with Ian Ball, the handsome English antiquities dealer with whom she's been flirting since the first book in the series, O' Artful Death. (The four books take place over a span of less than three years.) Sweeney, whose fiancé died a few years ago in an IRA attack, has finally healed enough to invite Ian to share her messy apartment. But she's still tense and drinking too much.

It's easier for her to relate to Tim Quinn, who's dealing with his own share of personal grief: His wife has committed suicide, leaving him with a young daughter. On top of that, Quinn's breaking in a new partner, a young woman whose emotionalism and inexperience frustrate him, perhaps because he's stifling his own emotions.

This is "Prime Suspect" territory, and Taylor covers it well in her solid, descriptive prose. When Quinn and his partner investigate the sex murder of a young Latina in a bad neighborhood, we sense that this mystery doesn't have to fit into the book's central puzzle in order to matter. It resonates thematically with aspects of Karen Philips' life and death, making it more than a distraction.

The mystery's ultimate solution is difficult to guess, but only because it relies on confusing, and arguably even implausible, motivations. A great character-driven whodunit solution bears a sense of inevitability; this one merely makes us feel manipulated.

Still as Death also doesn't offer the wealth of obscure lore about funerary art that made the earlier novels in the series compelling. The focus here is on ancient Egyptian artifacts, which, unlike mourning brooches or gravestone epitaphs, are well-trodden literary ground.

One intriguing thread is the notion of archaeology as a cultural violation that's analogous to a sexual one. In the novel's prologue, set in 1979 and narrated from Karen Philips' perspective, a young Egyptian dampens the student's passion for mummies when he tells her, "The white men are nothing more than rapists, taking what they wanted by force when they couldn't seduce my countrymen willingly." When Karen discovers the collar, which she suspects was illegally removed from a princess' tomb, she empathizes with the millennia-dead victim. Taylor raises, but doesn't develop, fascinating questions about the responsibilities scholars and collectors have to the long dead and their heirs.

This certainly isn't a "cozy" mystery. Like Archer Mayor, Taylor has a knack for drawing rapid character portraits of solitary, melancholic souls. And here she seems to be suggesting that Sweeney herself, despite her romance-novel heroine's name and good looks, is just a few whiskies away from becoming one of them.

From Still as Death:

Funerary art fascinated Sweeney because it danced on the subtle line between form and function. Gravestones were needed to mark the site of a burial, but they had become canvases for the stone carver's hopes and dreams for his own death. The ancient Egyptians had believed it necessary to entomb their kings with all of the things needed in the afterlife, but these common household items had been made glorious with gold leaf and carnelian, paint and beads.

Sweeney's exhibit would start with a room of artifacts that spoke to the elaborate preparations the ancient Egyptians had made for death. Alongside a sampling of sarcophagi from the museum's collection, she had included information about the elaborate process of mummifying bodies and a variety of canopic chests and jars used to hold the internal organs once they had been removed.

The exhibit then took a look at grave markers, including photographs of very early stone dolmens, and moving on to the American gravestones that were Sweeney's specialty, including rubbings, photographs, and castings of cemetery art from the earliest days of the American colonies.

Then came the postmortem photography, as well as other mourning items from the death-obsessed Victorian period. Sweeney had included a whole cabinet of hairwork mourning jewelry, and looking at the delicate pieces arrayed on green velvet, she couldn't help but think of Brad Putnam, her student and friend, whose murder she had gotten involved in investigating because of its connection with a collection of mourning jewelry. It was how she'd met Quinn, and as she thought of Brad now, she felt an overwhelming sadness at the pointlessness of his death.

The last room of the exhibit would include contemporary funerary art, loosely defined. Sweeney had lately become interested in impromptu memorial displays, the piles of flowers and teddy bears, liquor bottles and candles that appeared on the sites of highway accidents or murders. She still had to finish choosing the pieces for this final installment of the exhibit, but she was hoping to include some modern examples of mourning jewelry she'd heard about, pieces of plastic into which ashes were pressed, as well as some examples of memorial decals, the stickers that some teenagers had started putting on their cars to honor friends dead to gang violence or suicide.