AD Leonis is a nearby magnetically active M dwarf .
We find Doppler variability with a period of 2.23 days as well as photometric signals : ( 1 ) a short period signal which is similar to the radial velocity signal albeit with considerable variability ; and ( 2 ) a long term activity cycle of 4070 \pm 120 days .
We examine the short-term photometric signal in the available ASAS and MOST photometry and find that the signal is not consistently present and varies considerably as a function of time .
This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set which are separated in median time by 3.38 days .
In contrast , the Doppler signal is stable in the combined HARPS and HIRES radial velocities for over 4700 days and does not appear to vary in time in amplitude , phase , period or as a function of extracted wavelength .
We consider a variety of star-spot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots co-rotating on the stellar surface .
This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin-orbit resonance .
For such a scenario and no spin-orbit misalignment , the measured v \sin i indicates an inclination angle of 15.5 \pm 2.5 deg and a planetary companion mass of 0.237 \pm 0.047 M _ { Jup } .