Cellphone-mapping expert details locations of accused killers’ phones on day of Xiaopeng “Pippen” Yuan’s death

The cellphones belonging to Cameron Isaac and Ninimbe Mitchell were in approximately the same location where Xiaopeng “Pippen” Yuan was killed at the time he was killed, an expert said Wednesday during the murder trial of Isaac and Mitchell.

Rafal Dobrowolski, an expert in cellphone mapping and analysis, used Google Maps to show jurors the approximate locations of the cellphones belonging to Isaac and Mitchell in the hours leading up to Yuan’s death. Dobrowolski works in the criminal investigations unit of the Onondaga County Sheriff’s Office.

As the prosecution continued presenting its evidence in the case, others who testified Wednesday included a former Syracuse University student who sold marijuana to Yuan and several deputies from the Onondaga County Sheriff’s Office who collected evidence following Yuan’s death.

Wednesday marked the third day in the trial of Isaac and Mitchell, who are charged with first- and second-degree murder, respectively. Yuan, an SU student from China, was found dead on Sept. 30, 2016, at the Springfield Garden Apartments in DeWitt, where authorities allege that Isaac robbed and killed him. Mitchell is accused of acting as an accomplice.

Dobrowolski’s analysis of cellphones is possible because of cell tower information. When a cellphone sends a signal to a cell tower, it can then be traced to the approximate area where the cellphone is located.

Dobrowolski’s mapping of the phones belonging to Isaac and Mitchell showed that from 12:30-11:51 a.m. on Sept. 30, each phone was in a North Syracuse area that included Isaac’s apartment. Beginning at 11:52 a.m., the phones were tracked as gradually moving away from North Syracuse and eventually to DeWitt in an area that included the Springfield Garden Apartments complex, which is where Yuan was found dead. The 911 call reporting gunshots in that area was made at 12:51 p.m.

By 12:54 p.m., their two phones were located moving west from the Springfield Garden Apartments and arriving near a Cricket Wireless store, which is where Mitchell — under a false name — purchased a new phone for Isaac. The first cellular activity from that phone came at 1:20 p.m. on Sept. 30, Dobrowolski’s analysis showed.

Other testimony Wednesday revealed that authorities discovered gun ammunition in the homes of both Isaac and Mitchell when searching them in November.

Joseph Lamoureux, a deputy with the Onondaga County Sheriff’s Office, testified that he found several rounds of ammunition in locations throughout Isaac’s apartment in north Syracuse when he searched it on Nov. 17, 2016. Photos of that ammunition as well as photos of marijuana inside the apartment were displayed on monitors to the jurors.

Inside Mitchell’s residence on Willis Avenue in Syracuse, authorities recovered 10 rounds of ammunition, Deputy Timothy Hahn of the Onondaga County Sheriff’s Office testified Wednesday.

William Sullivan, the attorney for Isaac, pointed out during a cross-examination of Lamoureux that almost two months separated the day of the alleged murder and the day when authorities searched the residences.

“Those items could have been brought into the apartment at any time,” he said.

Another deputy with the Onondaga County Sheriff’s Office, Matthew Crowley, was among those responsible with searching Yuan’s apartment. He testified Wednesday that he recovered a BB gun from Yuan’s apartment as well as large quantities of marijuana.

On the morning of his death, Yuan bought four pounds of marijuana from a person who at the time was an SU student. The former student testified Wednesday that he began selling marijuana to Yuan in August of last year and later agreed to order a shipment from California of four pounds of marijuana that he would sell to Yuan.

The Daily Orange is not identifying the former student, who has since graduated, because he was never charged with a crime.

Prosecutors on Tuesday alleged that Yuan had informed Isaac in August that he was waiting on a shipment of 4 pounds of marijuana and that Isaac agreed to buy two pounds of it.

Between 10 and 11 a.m. on Sept. 30, after the former student informed Yuan that he had received the marijuana, Yuan arrived at the student’s apartment on South Campus. He took 2 pounds of the marijuana and returned around noon to pick up the remaining 2 pounds. The former student said Yuan was moving quickly when he stopped by the second time.

“He was kind of in a rush to get out of there,” the former student said.

The former student said he unsuccessfully attempted to get in touch with Yuan multiple times later that day. The next morning, authorities arrived at his apartment and informed him of Yuan’s death.

The trial resumes Thursday at 9:15 a.m., when the prosecution will continue presenting evidence.