Majumdar said Ziobryte pulled over nearby and made “multiple telephone calls” to family members, but did not call the emergency services.
She added: “At no point did the defendant return to the scene of the collision.”
Presiding magistrate Paul Fisher adjourned the hearing so a pre-sentence report could be prepared.
“We cannot rule out a term of imprisonment,” he warned the defendant.
Essex Police arrested Ziobryte on suspicion of causing death by dangerous driving shortly after the offence.
However, in January, the force said this charge was no longer being pursued.