Dr. Conrad Murray's attorneys are expected to begin their case Monday, a task legal experts say will be a big damage-control job if they hope to keep Michael Jackson's physician from being convicted of involuntary manslaughter.

The prosecution's four-week case will wrap up after cross-examination and redirect of key medical witness Dr. Steven Shafer. Shafer has repeatedly attacked Murray's account of how Jackson died. The propofol expert testified that almost nothing about the quantity of drugs Murray said he administered matched up with what was later found in Jackson's blood.

He also maintained that Murray was at fault for abandoning his patient -- and for failing to say no to Jackson's demands.

FULL COVERAGE: The trial of Conrad Murray

Prosecutors contend that Murray lied repeatedly. But even if his statements are true, prosecutors say the doctor's words contain enough admissions of gross negligence to amount to a manslaughter confession.

"They've got the defense in a trick bag," said J. Christopher Smith, a Los Angeles criminal defense attorney who has followed the case closely. "Whichever way they go, it seems like the prosecution is going to have a comeback."

The Murray defense team plans to call about 15 witnesses, including a toxicologist and Dr. Paul White, an anesthesiologist who has researched propofol. Those experts could argue that Murray's care of Jackson was unorthodox but not criminal. The charge of involuntary manslaughter requires prosecutors to show that Murray caused Jackson's death by committing a crime "not amounting to a felony" or while acting "without due caution and circumspection."

The character witnesses include an 82-year-old woman who knows Murray's work at a Houston charity clinic. The defense is expected to use their testimony to counter the portrayal of Murray as primarily concerned with collecting his $150,000-a-month salary.