Transrectal ultrasound (TRUS) guided biopsy is the standard procedure for evaluating the presence of prostate cancer. TRUS, however, has limited sensitivity to prostate tumors, nor can it differentiate aggressive cancer from non-aggressive ones. The emerging photoacoustic (PA) imaging combined with TRUS offers a great promise to solve this overarching issue, especially when powered by tumor-targeting contrast agent. In this work, we studied the feasibility of PA imaging to cover the entire prostate by using light illumination via the urethral track. Experiment was conducted on whole human prostates ex vivo. The light source was an array of light emitting diodes (LED) which has many advantages compared to solid state laser. The LED array was placed in the urethra, delivering light with fluence within the ANSI safety limit. A PA and ultrasound (US) dual modality system acquired the images in the same way as in TRUS. The imaging target was a 1-mm tube filled with ICG solution, mimicking the situation of a prostate tumor labeled with ICG contrast agent. The imaging results demonstrated that PA imaging can detect the ICG-filled tube at any place in the prostate, with an imaging depth over 20 mm. This study validated that PA imaging, when performed in a transrectal manner and combined with transurethral light illumination, is capable of molecular level imaging of the entire prostate noninvasively. The high sensitivity offered by PA imaging in detecting aggressive prostate cancer may contribute to prostate cancer management, e.g., enabling more accurate guidance for needle biopsy.