Before each taped interview, Jay was questioned by the detectives "off the record." As noted in Episode 8 of Serial,
"This is what’s called the pre-interview, and Trainum says, that’s where the mischief can happen. The contamination. Not necessarily intentionally, but it happens."
During the pre-interviews, the detectives worked with Jay -- for one hour, before the first interview, and for over three hours before the second interview -- to develop a statement that they wanted him to give. Once a coherent story had been worked out that met the detectives' objectives, the tape recorder was turned on, and Jay would tell the detectives the pre-arranged statement. The notes and maps reviewed in the pre-interview would be kept on the table, so that, when necessary, Jay could be guided through his statement, or corrected if he went off track.
The documents provided above, titled "Cell Phone Chronology 12/13 January 1999" and "Jay's Chronology" come from a Maryland Public Information Act (MPIA) request to the Baltimore Police Department. When the detectives are directly Jay's attention to various documents during his police statements, it is likely the documents used very closely resembled these. However, because Jay's statements significantly evolved with each iteration, a different timeline was being used for each interview, one that had likely been worked out during the pre-interview stage of the interrogation.
This particular Chronology contains details from all of his recorded interviews, but also contains details that Jay never gave in any recorded interview, leaving some question as to when it was drafted, or what the source might be for those details never mentioned by Jay . However, there is a big clue that this cellphone record was used in developing the statement given in Jay's second taped statement to the police, because it contains an error which Jay's story reflected. Call No. 28 -- the "come-and-get-me" call at 2:36 p.m. -- has the cell site location listed as "1500 Woodlawn Dr. (C)." In reality, the cell site for that call was the B antenna -- which, under a standard arrangement, would in fact have covered Jenn's house.
But thanks to this error in their call log, the cops detective mistakenly believed that the "come-and-get-me" call could not have been made from Jenn's. They thought it had to have been made from somewhere west of Jenn's house instead. So that's what Jay told the detectives, in his second statement. Prior to getting Adnan's call from Best Buy, Jay said, he left Jenn's house to go to Jeff G.'s house -- a house that was in an area that the detectives believed was in an area covered by 1500 Woodlawn Dr. (C).