He received a four-year ban for the use of EPO found in in-competition test in May 2022 and an additional four years for tampering with the doping control process, effectively ending his athletics career.

[14] At the 2019 Gold Coast Marathon, Robertson placed third in a time of 2:08:19, breaking his brother Jake's national record by seven seconds.

On 20 September 2022, Robertson was provisionally suspended without opposition for anti-doping rule violations (ADRVs), including the use of EPO found in in-competition test in May 2022.

He received a four-year ban for the use of EPO and an additional four years for providing falsified records and false testimony, effectively ending his athletics career.

[5][6] In September 2023 Kenyan newspaper The Standard reported that Robertson had been arrested after an AK-47 and 23 rounds of ammunition were found in his house.