DURHAM, N.C. — Forensic expert Henry Lee maintained that Kathleen Peterson's death was probably an accident but admitted Tuesday under cross-examination that he could not rule out bludgeoning as the source of blood at the scene.

"Nobody can exclude everything," said Lee, "but the pattern tells me [it] is more consistent with an accident."

Lee's concession was one of the few highlights in prosecutor James Hardin Jr.'s half-day cross-examination of the prominent forensic scientist. Lee, who drew few conclusions while testifying for the defense of novelist Michael Peterson, broadly attacked the state's handling and interpretation of the forensic evidence. 

Throughout, Lee's tack was simple: Focus on the "forest" not the "trees."

The "forest" in Peterson's case is the stairwell where Kathleen Peterson was found along with more than 10,000 individual spatters of blood  — the "trees."

Defense lawyer David Rudolf and Michael Peterson listen as their star witness is cross-examined Tuesday.

Lee, a renowned investigator who has testified at several high-profile murder cases, argued for a holistic interpretation of the scene, saying only general conclusions could be drawn, rather than a complete reconstruction of the victim's death.

Prosecutors, however, have sought to use separate bits of blood spatter evidence to prove Kathleen Peterson, 48, was murdered on Dec. 9, 2001, and to tie Michael Peterson to the crime.

Among the state's claims: Three spatters of blood high above the floor indicate cast-off from a weapon; blood spatter inside Peterson's shorts suggests he was standing over his wife when she fell; and spatter on the wall seems to indicate that Kathleen Peterson was standing in the stairwell when attacked.

Peterson, 59, could spend life in prison if convicted of first-degree murder. 

On Tuesday, Lee deflected Hardin's attempt to discern critical details of the alleged murder from the blood evidence.

While Lee was comfortable saying Kathleen Peterson probably writhed around before her death, coughing up blood onto the wall, he noted that a stringing technique used to determine a point of origin for multiple spatters of blood was simply not valid here.

"Some people use string, some people use a computer, I just go there and observe," said Lee. "My determination is as good as any other determination."

Because the scene was "dynamic," said Lee, little could be construed about where Peterson and his wife were when certain marks were made.

Blood spatter on Michael Peterson's shoes, for example, are next to meaningless.

"I'm good but I'm not that good ... I only can tell you this is a vertical drop. All we can say is the person is moving or the source is moving. This is a dynamic scene we cannot just look at one drop and say a-ha ... that's the limit of science."

In Lee's opinion, three spots of blood on the header above the stairwell were simply too small to have been cast off from the backswing of a blowpoke, the prosecution's suggested murder weapon.

Hardin also asked Lee how much he was charging Peterson for his work on the case. Lee, who said he routinely charges $500 per hour, said he'd only billed $27,000, including expenses, so far despite putting in 240 hours on the case. 

Hardin also attempted to rehabilitate his expert witness, North Carolina State Bureau of Investigation agent Peter "Duane" Deaver.

Deaver performed a number of experiments designed to simulate the state's version of events — that Peterson beat his wife to death on the stairwell landing — using props including a mannequin head with a wig, a sponge and a nearly identical replica of the stairwell constructed in his laboratory.

Under Hardin's cross-examination, Lee remained glib, calling Deaver's work "child's play" and "useless," and repeating platitudes such as, "If you want to study the tree, you want to study the whole tree, not just one leaf."

Despite his evisceration of Deaver's professional skills, Lee had presented the agent with a copy of one of his 30 books during a visit to the state laboratory. Hardin showed him the volume, asking why — if he thought so poorly of the agent's work — he had inscribed it, "To Duane Deaver.  Keep up with your good work."

"You'll probably find thousands of this same thing," said Lee, chuckling, "You can't write on the book ... 'you're totally wrong.'"

"It's just like I sent David Rudolf a book saying he was the best," Lee continued wryly, "but he's lousy."

Peterson's defense will continue Wednesday at 9:30 a.m. with a new witness.  The trial is being broadcast by Court TV.