Karen Read’s defense has called the expert believed to be its final witness as her trial in the death of Boston cop John O’Keefe, which began back in April, nears a close.

Prosecutors allege that Read, after a night out drinking, rammed O’Keefe in reverse with her Lexus and left him to die outside a house party during a record-setting blizzard on Jan. 29, 2022.

Dr. Andrew Rentschler testified briefly Tuesday afternoon and is expected to return to the stand for at least half a day Wednesday before the defense rests.

Rentschler joined Laposata and another defense witness, Dr. Marie Russell, in the opinion that scratches and cuts on O’Keefe’s arm were not caused by an impact with the taillight. The defense theory is that they were inflicted by a dog bite.

Read told reporters Tuesday that she would not be testifying in her own defense – and that Renstchler is the last witness her team plans to call.

“It’s the right move,” said Grace Edwards, a Massachusetts trial attorney who is closely following the case. “It is the sole decision of the defendant whether to take the stand. In this case, Karen would have to withstand a rigorous cross-examination by Brennan, which would include clips from the documentary and any other evidence they have that we don’t know about from other statements she made.”

She would also have to face questions about her drinking, Edwards said, which could break the “upward momentum” of her defense as expert witnesses have repeatedly contradicted prosecutors’ claims.